Episode 2, when Nanoha and Yuuno take a moment to formally greet each other.
Near the end of episode 5, as a showcase that the Intelligent Devices aren't merely AIs that follow their masters' bidding, Raging Heart takes the initiative in protecting Nanoha by surrendering a Jewel Seed to Fate, whose Bardiche was at scythe form poised at Nanoha's neck.
Episode 7, Arf rushing in to catch Fate after she'd warn herself out and collapsed retrieving the latest Jewel Seed.
Nanoha and Fate's relief once Raging Heart and Bardiche are fully recovered.
Episode 8, Nanoha rushing in to shield an injured Fate from Chrono. Even though the two girls are still technically enemies, that doesn't prevent Nanoha from being compassionate.
Episode 9, Alisa agreeing to take notes for Nanoha while she's unable to attend classes. Shows despite Alisa giving Nanoha the cold shoulder previously, that she still considers Nanoha her friend.
In episode 10, it's Alisa who discovers the wounded Arf and immediately decides to help her. Despite Arf's intimidating appearance in her animal form.
Arf humbly asking Nanoha to help Fate.
Arf: I know I don't have the right to ask you this but, but please. Please save her. She's all alone right now and your the only one who can help her.
Nanoha: It'll be alright, leave it to me.
Episode 13, Chrono promising Nanoha that he'll do his best to see that Fate isn't punished for what Precia forced her to do. Becomes even more Heartwarming in Hindsight since Fate becomes his little sister at the end of A's.
The final Sound Stage might as well be called "How happy can we make Fate?", with Lindy offering to adopt her, everyone throwing a party to celebrate her familiar contract with Arf, and the Loophole Abuse so she could have a talk with Nanoha. She ends up breaking down in Tears of Joy when she tries to express her thanks.
During the credits, Fate is shown having dinner with Arf, Chrono, and Lindy. It's probably the first time that she ever experienced what it's like to have a real family.