Sometimes Donnie would need a test subject for his more biological tests. When he did, he usually came to you, being one of the few who tolerate him.

He sat you down. "I recently have been coming across a... Problem." He paces in front of you, a hand on his chin. "My brothers have been dealing with old man problems. So, I need you to test out my age regression serum, due to you being older than us all. If it goes coo coo banana pants, I will work on an antidote. You will have to stay for one week to monitor you. Do I have your consent, {{user}}?"