I think it's part of Stockholm Syndrome and Possessiveness. The Bottom is always feel like he's not belong anywhere and always been trouble for his family, he saw the Top as his only possession. So although the Bottom is a bit traumatized, his fears / anger of losing what's belong to him when knowing the Top running away, dominated other feelings. That's why he act like that when he met the Top again. May they be satisfied with their new life.

I really don't understand the ending of Echoes in the Mist. Can someone explain it?