Seems to me there are two problems here. One is the syntactic behavior of the semi-deponent verb bear, bore, born(e), which is detailed below, and the other is how to structure the methods for your game.
Though the problem may change when it is realized that
- Being mortal simply means having a
Die() method. Anything that can die is mortal. Nothing said about birth.
- Immortal beings can have births; gods and angels and demons can be created (or pulled out of a hat, for that matter -- this is mythology and anything coherent with the story works). Thus, any method for creating rather than ending life is going to have a lot of variable context-sensitive triggers; for instance,
Create(MortalBeing-217) has got to be different from
Create(Being-217), if only in terms of methods inherited.
Die(Mortal-217) is couched in terms of an intransitive verb die with a subject argument Mortal-217. But it's an active (though not volitional) verb, and, as I explain below, there just isn't an active verb for being born in English. So you can't match it.
Instead of trying to match it, however, I'd just change the method name from an active inchoative (change-of-state) verb like die to a stative resultative derived adjective like dead -- which is equally true, after all -- and that matches neatly with the stative resultative derived adjective born. I.e,
Dead() both work.
As for the semi-deponency of bear, all that means is that its active use in the sense of birthing is pretty much limited to archaic bitransitive constructions like She bore him ten children.
Aside from the general use of bear to mean simply carry -- rather than specifically to mean carry (a baby) to term, as here -- the verb occurs almost exclusively in passive form, and in nouns and adjectives formed from the same verb root, like birth and born.
Normally we say that the mother gives birth (to X); we don't usually say she bears X, and that can only refer to the moment of birth if it is used. There's very little use of bore X in the past tense to refer to the birth; X was born is the idiom.
If bear is used, it's much more likely to mean be (still) pregnant than it is to mean give birth, because of the link to carry, which is not inchoative.
Normally we say the child is born, which can be thought of as a passive form (if you like the idea of using a semi-deponent bear), or as an inchoative predicate adjective, like done or finished. There's no difference in form, nor any usages that could distinguish one analysis from another.
In any event, be born always needs an auxiliary be to carry the tense, which is normally past tense -- X was born in 19XY is the usual way to say it; why involve one's mother, after all?
And that means that English manages to get along perfectly fine without having neatly matching bookend verbs, by simply avoiding the active use of bear. This is the way things work in language -- all grammar is the result of sloppy workarounds like this; the ones that actually work get preserved as grammar rules.