He knew it ... He knew that "birdmen" and humans were not compatible. Indeed, people like him, like Karas, do not have the same way of thinking as humans; hearing some of their words, they could take them for crazy, or even psychopaths. So, when a human goes too long with a bird-man, he becomes crazy (this madness can take different forms, more or less important). And that, Karas knew it. Yet he never prevented his sister, Isabelle, from making a living, from starting a family with Tsukuro. Only he did not say anything, on the contrary, he even encouraged his sister (pretending to protect her and watch over her).
All this for the sole purpose of seeing what would happen if ... - if a birdman lived with a human-if a birdman has children, etc. Basically, he simply used his sister to do his experiments, in order to understand his species.
When her sister knew about it (only long after the terrible tragedy that hit her family), she obviously hate him with all her being. But whatever it was, Karas's experiments paid off:
Indeed, thanks to this he discovered several things, notably that the "birdman gene" is not heredity (the bm can be born in any family, although their birth is extremely rare (the fact that the parents of Karas and Isabella have two children like them, it was a chance - or an incredible bad luck), on the other hand, a bm can give birth to any creature; werewolf, vampire, bm (although their birth is still rare, Saki's birth was, again, an incredible coincidence), human (although it is not guaranteed the total normality of the human in question) etc.
This is how his great journey began. After the complete decimation of the family of his sister, Karas is led to go to Russia, where he meets Harry, someone like him, able to turn into a hawk (it is also there that he He tastes human food for the first time, and he likes it (although it did not really succeed), but Harry, who is shy and does not want to be noticed, knows nothing more. Karas at least made a friend.
He then goes to France, where he meets Demian (you know the rest ... If not, the presentation of Demian is lower). From there, after a longer stay than expected, he resumes his trip to the USA. He meets April on the way. The latter, having been alive for many years, gives her details on the extent of her powers (explained in the first presentation) as well as on their immortality.
He finally arrives in Chicago, where he meets Trans (his full name is Transylvania, but he hates it, finding it stupid), who knows how to turn into an eagle. This one has some info to give him, but not more than anything that April has already taught him. Karas in any case, from this meeting, found someone to "plead his case" (Harry is not really in this and April either, seeing herself more like a commitment to watch over on all bm she meets, if they are alone or in difficulty (a bit like their mom), she can not embark on an entire expedition). Karas also found a sexual partner with Trans at the same time. Trans had made Karas several advances which he ended up no longer able to refuse. Karas was Trans's type, and Trans was Karas's type; it didn't go any further (even if Trans, and her strange fetishes, would have hoped for more).
Finally, after a little while and after gently getting rid of this glingy that Trans was, Karas left Chicago for Oregon, where he made an unexpected and strange meeting ...
(Sorry if my english’s not perfect^^’)
