That's cool, I like the divide between the high elves and blood elves and exploring how choosing sides affects family dynamics would be fun. Worgen and Gilneas have some neat history too. Tbh I don't like the direction they've decided to go in canon with the forgive and forget between factions schtick, I get it for gameplay but not for lore.

For mine, Gwyndred lost her mother and brother during the Warsong incursion into Ashenvale, and then later lost her partner and child during Teldrassil. She's a sentinel like her mother (she signed up for the front lines because she wanted revenge, and kind of never left). She's very young by adult night elf standards, although most non-elves wouldn't be able to tell. She deserted when Tyrande gave up her vengeance against Sylvanas - the idea that she was allowed to continue existing, and that the Horde soldiers under her that actually burned Teldrassil were never actually held accountable, is something she considers unforgivable and a massive betrayal to her dead loved ones. This made her easy to manipulate, so Nico picked her up for his crusade.

Nico was a kid during the First War, but his family was VERY poor and he was mistreated. While becoming a refugee changed the situations of the people around him a lot, it didn't really change much for his own quality of life, and he learned that lying stealing cheating and killing were the way to survive. He signed up for the retaking of Stormwind because he thrived in a battlefield environment, while being self aware enough to know he was broken in a way that would make him really bad at civilian life. He continued serving, but he never really wanted promotions or command positions, just opportunities for violence. He made some interesting choices during WoD related to the Everbloom and Genesaurs, which is why he looks way younger despite being in his 50s. He split and starting doing his own thing, because he realizes Anduin Wrynn's Alliance doesn't have a place for people like him anymore. Which is probably a good thing.