Michelle Welty felt a strong connection to the painting. He had a copy of it as a child and was somehow separated from it. The day of the explosion he was taking Pippa to see the original. He seems to have been disoriented after he was injured and makes references that seem to relate to his childhood "don't let them see it! they've stolen the rugs" and wants to keep the painting safe. He tells Theo to take it to Hobie and "put it with the rest of the treasures".
Kay To keep it safe. Welty was a protector. He either took care of people and objects, or found good homes for them. I like to think that he saw, in Theo, a glimmer of high intelligence that made him the right person to entrust with such a personally and publically valuable piece, but Theo was also the last conscious person in the room. If Theo had left the painting there, it was highly likely that it would have caught fire, or been buried or even trampled by rescuers.
Sarah Schmutz This was my question as well. If Welty was so injured, how did he even know the painting was near him? They were in the gift shop when the explosion occurred. Unless he had stolen it...? I kept thinking that when Theo told Hobie about the painting, it would unravel a whole other plot line b/c Hobie would be waiting for the one whom Welty had passed the painting on to. Alas, not the case. But I'd love to know the answer to this question.
Laura Although Welty's life is circumstantial, he provides a life and home for several people. Welty trusted Theo to go to Hobart & Blackwell.
Carol Yes, I see that Welty wanted to protect people and things. I guess I wanted Theo to do the right thing which to me was to return the painting. All along he knew he could turn it in no questions asked.