When Jasmine sees her mother's ghost in The Forests of Silence Part II. Also doubles as a tearjerker.
In The Lake of Tears, Jasmine's joy at reuniting with Kree just after the fight with Jin and Jod, and her insistence on using some of the nectar of the Lilies of Life on Kree and not on her injured shoulder. Also the joy on her face when she sees Kree healed and flying into the sky looking very happy.
Jasmine loses her dagger in the Shifting Sands, and is very distraught over it as it was her father's and the only thing she had left to remind her of him. While he's going into the Cone to retrieve the lapis lazuli for the Belt, Lief remembers about the dagger, sees it fall from its place in the tower when he takes out the lapis lazuli, catches it and brings it to the surface with him. The fact that he bothered to do that at all is quite heartwarming, as it shows just how much he cares about Jasmine. The moment when he gives the dagger to Jasmine is doubly heartwarming.
At the very end of the series, Lief's struggling to convince Jasmine to stay with them in Del, carefully coating his words so that he doesn't end up scaring her away. He claims that it's because she's needed to help set Deltora to rights, but really it's because he loves her and cannot bear the thought of her leaving him.
Lief's vague marriage proposal to Jasmine and her vague acceptance.
Lief: When the time comes, I will follow Adin's example and marry for love. If the woman I love will have me, of course.
Jasmine: She probably will, when the time comes.
Lief doesn't merely rescue Jasmine from the water when they are forced to abandon ship, but preemptively grabs her and falls out of the boat with her, knowing she can't swim. She insists he leave her as she is weighing her down, and he flatly refuses.
The whole reason the Shadow Lord nearly succeeded was because he knew that Lief would be hard to trick into the Shadowlands directly. Instead he chose to lure the more impatient and emotional Jasmine, knowing Lief would follow her.
Jasmine supporting Lief during the destruction of the crystal in Dragon's Nest. Lief can barely walk under the weight of the Shadow Lord's malice, but Jasmine runs to him and helps him stand to face the crystal, despite being heavily impacted by its evil herself.
Lief and Jasmine's reunion in the Dreaming Dunes in Isle of the Dead. Lief and Barda were missing for ten days and nearly everyone searching for them thought they would be lucky to find bodies, if they found anything at all. Jasmine never believed that they could be dead, and searched for Lief nine nights in a row using water from the Dreaming Spring. She finds him in a dream and a group immediately sets out from Tora in the morning. Lief did not know he was gone for so long, but he was unsure if Jasmine was safe or even alive. The moment when they see each other after days of separation is one of the most heartwarming in the series. (And it's one of the rare occasions on which Lief and Jasmine actually embrace.)
The hatching of the baby diamond dragon in Isle of the Dead, and the revelation that Veritas ends up caring for it. That in particular is truly sweet, as even though the dragon tribes were so suspicious of one another Veritas still chose to look after baby Forta after it turned out that her mother (the old diamond dragon) had died. It also symbolises the end of the dragons' animosity toward one another.
The scene in Sister of the South, just before Lief reveals the Shadow Lord's final, horrifying plan. Everyone is so happy and relieved to be alive, and have a celebratory feast while laughing and joking with one another.
The epilogue. Especially Lief and Jasmine's wedding and the revelation that they named their three children after Anna, Jarred and Endon. Also seeing that Barda ended up marrying Lindal and having six children 'all taller than their parents' really warmed hearts.
Once Thaegan was killed the first time Soldeen is freed from her curse and transforms back into his true form of Nanion. The look on his face when he sees his wife returned to normal is enough to bring tears to your eyes.
The end of the episode "The Heavenly Stone", when Lief gave Jasmine back her knife after nearly falling to his death in order to get it back.
In the anime, after Lief drinks form the Dreaming Spring and watches his father in prison. Lief looks on as his father refuses to give up on his son.
Jarred: (to himself, unaware his son can hear him) Leif, Barda, it's good to hear your alive. And not only that, that your actually succeeding in getting the gems.
Leif: Your right father, we are. We've already got four and their on the belt. We're on our way to Dread Mountain right now to get the fifth, and we're moving as fast as our feet will take us. So hang in there, we're gonna be back before you know it. Don't give up.
Jarred: If I could talk to you, I'd tell you, never give up, and I'm fighting my fight as best I can. You must remember that what your doing is fighting for the freedom of all Deltora.
Leif: I will father.
Prin swooping in and saving Ri-Nan in the episode "The Great Gellick!", despite the fact that the Dread Gnomes had hunted her kind to near extinction and treated them like animals, and that Ri-Nan had just betrayed Leif and the others to Gellick.
Small moment from episode 39, when Neridah rushes to Leif, it's to ask him to save Doom and not herself. Also Tora's magical Good Hurts Evil barrier in the city's main tunnel (which kills those who are evil when they enter) kills the Grey Guard chasing her, but leaves her unharmed. Proving that while Neridah can be a Bitch in Sheep's Clothing at times, she's not a complete monster.
The anime series had a really good example. At one point Barda has to retrieve the Topaz (the one that lets you see dead people). And just as he gets ahold of it, it activates. Giving him the chance to be reunited with his dead mother. Now I'll be the first to admit I often found him to be a Flat Character, but watching his reaction at seeing his mother again was very heartwarming. Also counts as a Tear Jerker moment.
In a strange way, the scenes of Thaegan with her children. They are a weird, evil, sadistic, but a strangely close family. (In the anime at least. The book versions are decidedly different.)
Example: When Thaegan is revived the first time, she reunites with her children and they instantly crowd her like any young children whose parent has come home after being away for a long time.
In her death, Thaegan is surrounded by most of her children (except Ichabod). She asks why they would sacrifice themselves with her to which they reply, "Because you're our mother."
Endon and Jarred greeting each other after Lief and the Kin rescue his parents from Fallow.
Star of Deltora
Shadows of the Master
Captain Gripp enrols Britta in the Rosalyn Trust competition without her knowledge, and only tells her the day before the beginning of it, because he knows that Britta would find a way to get out of it or plain refuse to enter out of fear and he knows that this opportunity is what Britta truly wants and needs.
Jantsy's obvious love for Britta. It's clear that he thinks the world of her, though she doesn't seem to reciprocate the feeling just yet, and cares enough to come to the harbour to farewell Britta and support her as she leaves to compete in the final leg of the Rosalyn Trust competition.
Especially this line:
"Because you are beautiful, Britta. Because your face is so full of life, and your eyes seem to sparkle when you speak."
And then there's also the moment when Lean Alice confronts him and warns him that Britta does not walk alone ( hinting at the shadows that follow her everywhere). This is his response:
"She certainly does not! I am with her. And no one will insult her while I can prevent it."
And when Britta goes to Captain Gripp's Jantsy promises her that he will wait outside and walk her home when she is ready.
Jewel's reaction to her receiving an interview in the Traders' Hall, and later is accepted as a finalist. It's clear that she never expected to make it so far.
Captain Gripp's child-like glee at having figured out Britta's coded message to him.
Jewel cheering for Britta when she makes it just in time back to the Traders' Hall to hand in her trade. It really heartwarming, considering that they are both rivals for the apprenticeship and Jewel should really be hoping for Britta to lose.
Then there's her waking Britta up in time for the competition, when she could have left her to be late and taken out of the running, and also her warning Britta not to touch or turn over her exam paper before writing time lest she be disqualified. Jewel didn't have to do any of these things, and it would have benefited her more if she hadn't.
Britta calling her sister 'Marthy'.
Britta's response to Zoolah's insults about her family:
"Shut your mouth! They are both worth ten of you!"
Even after seeing her mother spurn her Britta still shows that she loves her mother and sister dearly.
Britta missing Zoolah at the send-off party for the finalists at dawn, even after the woman had been so horrible to her and threatened herself and her family.
When the Star of Deltora sets sail, Britta is feeling sad at Zoolah's death, and doesn't expect anyone to be there to farewell her, given that her mother has spurned her and her sister isn't brave enough to defy her and come when the harbour is forbidden. Then she sees Captain Gripp and Jantsy (who she didn't think would make it) on the shore waving at her and wishing her luck, and it cheers her right up.
After Britta apologises for ruining Sky's plan to fool Vashti in Maris, Sky's eyes soften ever so slightly before she puts up her guard again.
Britta trading with the turtle-people for Sky's life.
Britta's worry for Sky after Sky is outed as a boy and locked in the lock-up. Made even more so when Jewel comforts her with uncharacteristic gentleness about it and later advises her on what she should do about her ruined hair and the amber mark on her forehead.
The Towers of Illica
Dare's fear and worry for Britta after he sees the Wraiths' increasing interest in her and realises that she will be in danger if she comes too close to the Hungry Isle (since she'd be compelled to go onto the island and claim the Staff for herself). Even after all he's been through and how numb he's become he still cares enough about his daughter to not want her to share his fate.
Sky warning Britta about Bosun Crow. He's so earnest and serious in that moment, and without the usual Jerkass Fašade he puts on in front of others. After Britta abruptly tells him that she wants to be alone, his facades snaps into place again, and the reader can see just how much he'd opened himself up to Britta in those few moments.
Directly after that, Sky telling Britta about A Trader's Guide To Illica, to repay her (or so he says) for her saving his life on Two Moons.
Sky and Jewel rescuing Britta after she is pushed overboard by Bosun Crow. It's this event, and the conversation they have straight after it, which causes them to go from wary competitors to firm friends.
Jewel moving back into Britta's cabin after the attack on the deck, just so Britta can be better protected against Bosun Crow.
Sky giving all of his shore money to Britta so that she has money to use for trading on Illica.
Sky holding Britta after she collapses in the Blind Tower, and his apologising to her for not realising that she'd never seen a dead body before.
Sky helping Jewel sneak back onto the Star after she flees her host's Tower.
After realising that Britta has lost her one chance of winning the Rosalyn contest (and also realising that she wanted to win more than anything) Sky gives her (or trades, rather) an odi hairclip which Britta can use to win the competition. Even better, the odi on the hairclip are arranged in a pattern which means 'forever', and Britta also recalls that odi ornaments are often prized as love-tokens, which possibly hints at romantic feelings toward Britta on Sky's part.
At the very end of the novel, Sky telling Britta to be of good heart.
Basically all of the True Companions moments between Lief, Barda and Jasmine.