It's not your fault nobody loves them, nor should you be stuck talking to them. That said, keep an eye on him/her; since they have no real family of their own, they may try to coopt yours. If this happens, snag some of your grandmother's jewelry, which she's likely owned for 80+ years, and plant them on your friend. The accusations of stealing and ruining Thanksgiving will teach them to not have anyone who cares about their well-being.
Uncle: Remember that Thanksgiving where we all played touch football and Jimmy kept running backwards. That was great. I love you guys…Could you pass gravy?
You: Looks like we're out.
Uncle: Obamacare strikes again.
Sure the conversation will be fine at the start, with your adorable grandma doling out praise, smiles, and second helpings of sweet potato casserole. But it will quickly turn to how she's led a good life and is "ready." She won't specify what she's ready for, but she will make prolonged eye-contact with you when she utters it and will slowly nod and OH MY GOD GRANDMA WHAT YOU ARE IMPLYING? I'M NOT SOME SORT OF MONSTER.
After drink five, everything she does or says is her forced attempt to merge the families. Hate to break it to you, ma'am, but this will never happen. Every drunken attempt to get us to play Jenga: Family Edition is another reason why we will never emotionally let you in.
He's probably a really good guy and will do everything he can to make up for his embarrassing mother. And that's precisely why you should stay away. As a decent human being, he's going to exert all his energy in impressing everyone with his good manners: doing dishes, offering to get others drinks, removing the overflowing wine glass from him mother's kung-fu grip… you know, bullshit things you do when trying to get in people's good graces. The more he does, the worse you look. But if you're never in the same room as the guy, you can remain lazy and mooch off his desire to be accepted.
A real downer, this one. Unless you're into hearing people talk about how their mashed potato recipe is far superior because that's what OBVIOUSLY everyone wants to talk about. Got that, Linda? Jesus Christ, why can't you just accept that everyone in this crazy little world is different and goes about thing in their own manner. And yes, we know, it wouldn't hurt anyone to offer a vegetarian option, but that's not how this house does it, okay?
Sorry about that. Where was I?
Shit's about to get real. Calm him down by trading your cousin's Fruit Loop necklace for his possessions/land.