It's a little hard to determine character quests without really fleshing out your character and their background first. I do not like character-specific quests in general unless they add to and develop the character-some mod npc's have pointless quests that do nothing but give that character a moment in the spotlight and get the party some loot and experience, and others have more personal quests that add to and shape the character in question. For example, Xan's quest with Elhan in SoA is a good example of the former-there's really no point to it in terms of character development. Adding another layer to the siege of Suldanessellar is good, but there's really no grounds for it being a Xan quest, as it adds little to nothing to Xan's character and what the player knows/thinks/feels about him. A good example of the latter type of personal quest would be Sarah's quest, which doesn't really have any gameplay point, but resolves some important issues in Sarah's past and really helps shape her as a character. Or for non-mod examples, Nalia's quest string is an example of the former, and Jan is an outstanding example of the latter (much as I might hate all the to-ing and fro-ing of Jan's quest).
I would write a character quest if and only if it serves a purpose in developing Emmeline as a character, and if you do decide a quest is in order, think of it from a character development standpoint first. Everything else, a player can alter as they choose with the console and Shadowkeeper.
It occurs to me that another viable approach is to set up a quest so that it initially stems from the NPC's being in the party but rapidly ceases to be a quest specifically for that NPC (I'm more or less doing this with Arkalian and a couple of her major quests; she doesn't actually need to be in the party to complete them after a certain point, though they lose quite a bit without her).