Duke introducing the Joes to his parents as his "new family." Manly Tears.
Not part of the show's canon, but the dedication to character designer Clement Sauve, the show's character designer who passed away earlier this year, at the end of "Brothers of Light" is this for the show's entire production crew.
After the Joes win yet again in "Castle Destro," the Baroness expresses concern over Cobra Commander's reaction. Destro states he will take full responsibility for the failure in order to protect her.
The relationship between Tunnel Rat and his brother Teddy Lee. The two are completely dedicated to each other.
Likewise, Roadblock and his cousin Heavy Duty. They eventually admit that they are both a little jealous of each other, the former of the latter's academic success and the latter of the former never losing touch with his family. Their grams, too, when she settles Heavy Duty's last grievance over their grandpa's inheritance, which Roadblock lets HD keep since the latter has less things to remember him by than RB.
Also, Heavy Duty's code name, which he himself asks to be referred to as. Turns out, Grams gave him that nickname as a baby due to his diaper filling tendencies. Despite it being an Embarrassing Nickname in origin, he chose to keep it as a means of keeping his Grams close to him.
Roadblock:(to Heavy Duty) "The way I see it, home never leaves you, no matter how far you run."
Grams then has Roadblock invite the Joes in for supper. And they are able to have it without interruptions this time, too.
Crossing into Tear Jerker territory, the flashback with the death of the Hard Master. He took a sip of tea while Snake Eyes was about to do the same and, as he realized he had been poisoned, the Master still had the lucidity to knock the cup out of Snake Eyes's hands to avoid him the same destiny. It later turns out Snake Eyes's cup had no poison in it, but it doesn't make that last act of affection of the old man for the boy who changed him for the better less poignant.
Duke trying to keep an injured Scarlett awake in "Going Underground" via positive encouragement.