Let’s guess. I know a lot of us have different opinions on this, and so far it’s been hinted about, but not actually revealed in the text. (Remember in one of the bonus stories when he was about to reveal his project in his inner monologue, and then the Aberrant siren interrupted?)
Here’s what we know:
-he is researching old texts to find his answers
-he is translating pre-cataclysmic texts
-???
I’ll let you all start…
Whatever it is, I have a feeling it’s going to be… morally questionable? 
How dare you imply that Thaddeus Lacer, war hero, possible Red Guard Agent, and friend to all might posses anything other than unimpeachable morals? That sound you all heard was me clutching my pearls. . .
That said, the thing that I think he wants the most out of life is more time. With more time, he can achieve all his other goals of amassing power and knowledge, and he knows he’s almost halfway through his life. I have several ideas about how he wants to achieve that goal. Possibly learning what triggered the cataclysm? The secrets of time travel? Possibly by turning himself into an Aberrant? What do you guys think?
I think if he ever learns about the spell Siobhan did for Bear, he’s going to be sorely tempted … and that assumes whoever is behind the vanishing homeless population isn’t already aware of the spell.
Blockquote I think if he ever learns about the spell Siobhan did for Bear, he’s going to be sorely tempted
I think finding a bunch of stray humans willing to sacrifice their family jewels to extend his life may be considerably more challenging.
My current pet theory is that he’s researching the origins of aberrants and the cataclysm, which are one in the same.
Basically I’m guessing that prior to the cataclysm when break events happened, people didn’t become aberrants, they became titans (or were put on a perilous path towards becoming titans if they could maintain enough control).
This explains why all the titans gradually went mad and died out post-cataclysm, but also why there don’t seem to be any powerful pre-cataclysm aberrants still around, since I doubt that aberrants would age, and they’re very hard to kill.
Within this theory, pre-cataclysm titans were kinda like vampires in that they would keep their minds, gain power, and and become essentially immortal, but also be cursed with insatiable, destructive hunger that colored all of their experiences from that point on and made them either an outright threat to humanity or a ruling class over humanity that leveraged their strength to have their demands met.
Then the cataclysm was either an attempt by them to free them of their hunger (manipulating the laws of the universe such that magic itself supplied infinite power to those who broke, rather than forcing them to constantly consume matter) or an attempt by ordinary people to free themselves of these insatiable, magically powerful giants (manipulating the laws of the universe such that those that go through break events don’t retain their minds and are unable to guide their forms).
And then, if that is true, Lacer would be researching the cataclysm in order to find out how to literally abruptly reshape the laws of magic. it would be why he knows so many pre-cataclysm languages as well as ones from the immediate post-cataclysm period and why he is such an expert in Titanic history and lore that he surpasses professors who specifically dedicate themselves to that field, but also maintains an active interest in aberrants and those who might safely be able to cast through their own bodies (the Nought bloodline).
He thinks that the Nought bloodline surviving changes everything, and also that he would love to use the Raven Queen as a test subject if it wouldn’t be so dangerous because he thinks that the Noughts might be able to retain their sanity during break events and still become modern titans.
Any research on this subject would, of course, violate his Red Guard oaths, since the knowledge would be inherently dangerous to humanity, but he wouldn’t let a little thing like that stop him.
“Willing” is probably the only incorrect part about this assumption. I’m not sure he’d care. He might even think he was doing those people a favor - especially in a world where many are one child away from starving. (I’m not saying that’s right, just that I think he views most people as worthless.)
Okay, I really like this. I could maybe see that - we don’t have enough info about Titans to get us any closer to this, but I’m going to keep it in mind. However, one thing - do we know there are no pre-cataclysm Aberrants? Are we sure?
It’s possible that Aberrants were the cause/result of the cataclysm, but I don’t know. I am still wondering if Ilma was correct, and that people were messing around with powers better left alone. I hope we get more hints in the next books!
Aberrants don’t seem to have been recorded pre-Cataclysm, but its hard to tell for sure - it certainly seems as though Aberrants are more frequent in the modern age than when Myrddin was around - but that might just be because Siobhan hasn’t made extensive research of them during the Blood Empire or earlier.
There’s very little to go off of, we know he’s translating pre-cataclysm texts which we can infer means he’s been reading them and was spurred by their lacking quality. So the question is why is he researching pre-cataclysm works. It could be an attempt to piece together the why of the cataclysm, it could be researching the origins of some pre-cataclysm artifact, or it could be simply to satisfy his own insatiable curiosity. The truth is we really don’t know and I can’t think of anything that might point one way of the other. Besides maybe that one quote early on about investigating confusion he had with Sebastian. I unfortunately can’t remember what chapter it was from but he shied away from saying too much. It was suspicious.
I still think he’s trying to figure out where magic came from. What sparked magic?
Or maybe what caused the cataclysm so it can be avoided in the future.
We know he has focused on [PC] languages, he says as much in one of his POV.
And he seems to be very interested in understanding the concept of all magics, even if it’s just the most basic of how it functions.
Remember how he was able to explain the benders right off the cuff? And iirc he’s also hinted at knowing other forms of magics, just the concepts, but enough to explain.
Other than being an in suffering know it all, why?
I honestly think he wants to know where magic came from, if it is infact intelligent.
After all, magic is the only common link of aberrants (that we know of) and we know that the red guard has a vow to protect the world from stuff that can destroy said world.
So understanding where magic comes from might answer the question of just how dangerous magic is, and also, maybe how to better control it, or at least help minimize outbreaks.
…
And I mean, I can totally see him learning stuff just because he likes knowing
But learning PC languages would help him try to pinpoint when whichever culture started using magic and how
And the how they did it might help him find the absolute start.
I stand by the he is willing to talk to aberrants and the like as normal beings, because he believes (and prob rightly so) that this will make him favorable in their eyes and therefore willing to impart some wisdom that they wouldn’t otherwise share.
Personally, I think he might be interested in a different convention of magic compared to the ones being used now which has sacrificial circles, written word, geometry, numerology, glyphs, etc.
It is mentioned that most esoteric spells are pre cataclysm and passed down familiarly by word of mouth. Which is why they’re so scarce and closely guarded.
What’s interesting to me is that esoteric spells don’t require the normal convention to cast like modern sorcery. They are essentially like free casting in functionality.
Then, given Lacers reputation as the youngest free caster, it seems like an appropriate connection that he is looking for a way to access magic more ephemerally like esoteric spells or maybe come up with a whole new magic system entirely.
From context clues, I believe that the way magic is performed today is not the same way it was done pre cataclysm and this suggests more mysterious aspects about magic or that it is shaped by perception (which we already know) but so much so than is thought - to the extent that even the systems of magic aren’t fixed, but influenced by those who use it and how they think about it.
Thus, magic could have been performed very differently then. Perhaps it required less sacrifice, components or setup and thus, more convenient to use? More intuitive and less structured? (Soft Vs hard). Maybe it could achieve more?
This might suggest that free casting can be achieved without the higher power level that is referenced to be needed and for me, that has certain implications about the will and what it actually is and does.
Also it’s perceived understanding of how it’s meant to function. Perhaps it’s not being utilised the most optimally with the way modern sorcery is now.
(I have many thoughts on this but if I write it all now it will probably make this too long for anyone to want to read)
This also aligns with his unusual interest in aberrants (maybe that’s the whole reason he is in the red guard to begin with). They think about, are affected by and access magic in an entirely foreign and alien way.
Another theory is that more planes exist than the ones that are already known and the cataclysm is a result of some terrible disaster regarding one or multiple of those planes in some way - leading to catastrophic failure.
Perhaps his research involves trying to design spells to access those different planes?
Like, I believe that the black wastes are an example of catastrophic failure regarding one of those currently inaccessible unknown planes.
See that, that aligns with what I have been considering. That makes so much sense to me.
We’re talking about Lacer here.
He has access to the police. Who would complain if convicted rapists started losing their balls before they got hanged?
Late to the thread but…
What if the Cataclysm came about because magic changed?
That creepy spell that Siobhan cast to create her glyph:
“Mark me, scarred and tattered witness of days, One who weaves the thread that still is woven.
Heed me, one who howls unheard. I command you. Grant me eyes that see.”
We know the magic is sentient in some sense - what if someone literally became the fabric of all magic? It could be the largest break event ever or it could be that they were bound, willing or not, to become the keeper of records, witness of days, the one who keeps track of ideas. The weaver of threads that are still woven, recording everything on the tapestry of magic that evolves as people evolve.
I’ve always felt that that spell was her making herself known to magic and begging it to allow her a minuscule crumb of its power - the ability to know one glyph intimately, wherever it’s used.
If we know the magic changed drastically before and after the Cataclysm doesn’t it make sense that it could have been a change in magic itself that precipitated the shift?
I certainly wouldn’t, hehe.
As I mentioned above, I think that she will get rather more than an awareness of one glyph…
i think a number of coppers, such as Robards and Titus, would object to anyone being used for actual blood magic. Whether they were going to be executed or not.
Maybe…but do they have to know?
They most definitely would not know about it.