quagmire
/kwagmyer/ - noun

a person you'd prefer not to be around and who you really don’t want to be stuck talking to alone at a party because:
1.) they are impossible to read, and you can never figure out what’s really going on with them

2.) they will lead you into awkward, complex, and sticky situations where you’ll somehow end up knee deep in shit that isn't even yours
Example #1
"Bertha's been a total quagmire lately! I never know if she’s happy or pissed off, does she want me to talk to her or should I just shut up?!”

Example #2
Michelle " So how was the party last night, did you have fun?" Jody "Yeah it was super fun...until I got stuck talking to this quagmire. One minute I'm having a drink and chatting next thing I know, I'm in the backyard, mud wrestling a midget on a slip-and-slip!" Michelle "What the actual fuck...?" Jody "I don't wanna talk about it anymore..."