Definitely when #1 consoles Das Bo Shitt about his broken computer by giving him money to see a movie and the hug after surprising him with an entirely new machine when he comes home in the "200.000 subscribers milestone" video.
Speaking of broken computers, Das Bo Schitt's computer in real life was starting to become worse for wear, and he made a video asking for donations for a new computer so he could turn his career around from his current job as an unarmed night guard. He hit his funding goal in around an hour.
Hell, the mere fact that they teamed up at all is heartwarming, considering their history. It's especially big of Chuckles, considering the many times where Dr. Hax would go after him for a Felony Misdemeanor, or for no reason at all.
Episode 14 makes it seem that Chuckles is now Dr. Hax's pupil, and it's actually kind of sweet to see the mentor-student dynamic between them.