Anytime the two of them are genuinly nice to each other since they usually pretend to be Vitriolic Best Buds.
The number of times Danny gushes about Space Quest and Sierra Games in general shows that even after twenty years he still loves them.
Ross' encouragement of Arin through Veni Vidi Vici in VVVVVV is genuinely really sweet.
The special version of the Stanley Parable demo they received that was specifically dedicated to Steam Train, and to Danny and Ross.
The first episode of Leisure Suit Larry has Danny back and Ross is so excited and acting like a happy puppy.
Doubles as a Tear Jerker. In the second (and final...) episode of "Oregon Trail", Danny told a story about how when he played the game as a kid in class, he named the characters after his family members. When the character named after his mom drowned, he pretended to go to the bathroom and left the class to cry for about ten minutes because he was so upset about his mom "dying".