Gouken's return to Ken and Ryu. In the original Street Fighter IV, Gouken risks his life after having just awoken from a ten year coma in a battle with Akuma, for the chance to seal away the Killing Intent within an unconscious Ryu. Then he disappears before Ryu awakens. Later, He appears on a cliff, looking down at Ken and Ryu, resolving to test their strength and see how they have grown as men. When he catches up with them, they beg him to stay with them for awhile, only for him to tell them that they have grown and no longer need a master to take care of them.
Guy's continued concern for his best friend Cody, even after all that's happened between them and how Cody has changed.
Both of her endings, too. In IV, Ryu shields Sakura from BLECE before destroying it, then she helps him walk out of the S.I.N base. In the second part of her Super IV one, as she's jogging underneath a local bridge with her Akita dog... she sees Ryu walking towards her, and she runs to him in joy.
In the Udon Street Fighter IV comic, El Fuerte and Rufus end up on a Ninja Warrior-like show along with Sakura and Dan. Sakura talks with Fuerte and finds out that he's a big fan of Rainbow Mika. When Crimson Viper shows up to kidnap Sakura, Fuerte leaps to her defense. A few months after the incident, Sakura and her family show up at his restaurant in Mexico... and bring Mika along with them.
Sagat's SSF 4 ending, where he meets up with a group of Thai childrenand shows them kindness. It's really adorable to see the giant Sagat holding a little girl's hand as they walk peacefully through the rice fields with another kid and the local elder. Then it's subverted when we see it from Adon's POV in his own ending sequence: while the scene is still a sweet one for the viewers and Sagat himself, Adon is far more cynical and sees it as the proof that Sagat has grown way too soft.
Abel [as he's welcomed by his puppy ]: "...I'm so glad to be back home."
After winning the rival battle against him in Ultra, Rolento offers Cody a chance to join his army and turn his life around. Rolento is no saint, but he's shown to be a competent and respected leader. Him reaching out to Cody is very telling of how much he respects his former enemy.
With the voices set to Japanese, if Ryu uses an Ultra Combo in his rival fight with Sagat, he calls Sagat "nii-san" ("Older Brother"). It reinforces that the animosity that fueled their relationship in II and Alpha is completely gone, and the two are good friends now.