Iām not sure how much this will help, as itās pretty generalized advice, but I think itās quite the boon for situations like this.
At the end of the day, the characters we play, regardless of their class, are still people. Whenever youāre having trouble configuring how theyād act, remove all the extraneous stuff; think of them just a relatively normal person and alter the results later.
Also here are some tidbits about Death Knights that may also help:
Third Gens, and presumably Fourth Gens (the core and AR player DKs), possess an inborn vice called the Endless Hunger. This compels them to cause pain and suffering upon others, lest they themselves suffer maddening pain until they do. The frequency of this is unspecified but I personally liken it to the livingās requirements for sustenance.
A common misconception about them is that theyāre emotionless. Itās more likely that their condition amplifies their negative emotions.
āAll that I am: anger, cruelty, vengeance - I bestow upon you, my chosen knightā
-From the quest āIn Service Of The Lich Kingā, spoken by the Lich King (Arthas) himself.
This of course doesnāt mean your character has to be an a-hole now, itās just something to consider.
Overall youāre technically free to do just about whatever. Keeping those previous two things in mind however, Iād say, is rather important.
Iād also say that depth is especially useful for Death Knight characters. Planning the characterās old life makes deciding how they act now much easier, I feel; unless you go the angle of the character having little recollection of who they were upon being raised, though from what I can tell that doesnāt seem to be the case here.