Had an idea for at least 4 characters I want to try play if I got the chance.
1 character was going to be a knightly / honourable warrior of Khorne, who's minion would be a squire.
Another was going to be a Tzeentch sorcerer of some kind followed around by basically a walking-encyclopedia for a minion (some kind of servitor or something like the Sage model for the Witch Hunters army in 40k).
Another was going to be a Nurgle mad doctor / scientist who's probably many minions would all just be his bodyguards and test subjects in one (think high-toughness, low-intellect characters for him to try new plagues on).
And another character I think that would be fun to roleplay would be a Chaos Space Marine who's minion is another Chaos Space Marine who's probably thinking of one day taking over my character's place through eventual betrayal. Might be hard playing with a minion who probably would kill you with enough failed Loyalty tests, but if it happens, I could probably talk to the GM about then making my new character my first character's minion after he took over.