Hmm... Considering a stupid human Summoner (unchained). With both an eidolon and a familiar. They are both smarter than the PC and constantly tell him what to do.
The familiar could be a decent scout.
The eidolon could be built for melee combat or as a face character (if the group doesn't already have one).
The familiar would be a mangy cat that isn't very nice (like all cats). So would tell the PC to do nasty vindictive things and over-react all the time with violence.
The eidolon would be a lovable nice guy always trying to find the peaceful solution to everything.