I very much doubt it's an attitude. He might have a urinary tract infection or is afraid of your mother and therefore pees out of fear. (I once found a stray dog that was so afraid of being approached that she peed right where she was sitting
) He might also be marking if he's not neutered, or it could simply be that he's not fully potty-trained yet.
This post makes me very sad and angry for both of your dogs. I say "both" because Lina is also at risk of abuse in the future. If I were you, I would take charge of the training and also pay the vet a visit. If this doesn't work out, I would look for a humane shelter/rescue that would do their best to find Luke (and possibly Lina) a better home. From the little you have told us, I think re-homing them would be the best thing to do. I hope the situation improves, and I also want to wish
you well. The three of you will be in my thoughts. Please keep us updated if you can.