Just seeing Klaus save a young slave boy in the 1800s from being whipped. And bonding with the boy as both being outsiders beaten for being different. The parental smile on his face as he names him Marcel is both uplifting as we see the hidden depths of humanity that Elijah and Caroline see in him, and somewhat bittersweet as, Klaus being Klaus, we know it won't end well.
Hayley handing over the daggers to Rebekah after the latter saved her. It's good to think that Rebekah might have a friend.
Marcel saving Davina's life; much as Klaus freed him from slavery, he sought to save a child he had never met.
Marcel first bringing Davina to the Attic that would become her home, he's just trying his best to make her feel safe checking to see what she likes to do. When she mentions art he offers to buy out a store just for her and maybe get her some drapes for her drafty, cobwebbed and dusty new home. The best part he seems to act like a big brother trying to comfort a girl recovering from a traumatic event, and clearly has no idea what he's doing but his best anyway for her.
What does Josh do when he finds out that Davina is on a mission to kill Klaus? Does he warn her that if she succeeds he will die? No , he tells her to give it all and don't hold back. Because her safety and freedom means more to him then his own life.
He later tells her that he loves her and so does Marcel
Marcel working with Elijah to protect Davina, they may not like each other very much but they are both willing to find common ground where she is involved.
Marcel rushes to save Rebekah from Klaus after he finds out that she and Marcel had used a witch to summon Mikael to New Orleans in 1919 to kill him. Klaus, of course, beats him readily and says he'll kill Marcel in front of Rebekah. Immediately, Rebekah tells Klaus that summoning Mikael to New Orleans was her idea. It's a testament to how much she loves Marcel. Prior to his attempt to rescue her, Rebekah was refusing to beg Klaus for mercy for herself, no matter what horrible fate he had for her.
1.15's flashback shows that Klaus had finally given his blessing for Rebekah and Marcel to be together. Too bad Mikael had come into town on that day...
Davina comes back to life after Celeste is killed for good. Marcel's face is like the sun coming up as he comforts her and says he won't let her be hurt again.
Elijah would rather risk true Death, and the wrath of his Father than turn against his brother.
Essential powerless Marcel still enlists Josh help in order to make sure that Davina is okay. Not because he needs a weapon because he still wants to look out for her.
Seeing that the witches have ordered for Davina to receive no gifts, Klaus takes it upon himself to give her not one, but two. First he pardons her best friend Josh, and then he gives her the spell to create a daylight ring for him.
Klaus turning Camille's uncle into a vampire so she could say goodbye.
All throughout the season, Hayley and pretty much everyone in the cast has been in doubt over how well/terrible a father Klaus will be. Hayley in particular has been wondering what's to become of her once she's given birth and has no other reason to stick around. Not only does Klaus tell her emphatically that their baby needs a mother, but he's been decorating the nursery. Complete with a crib, twinkling lights and his most recent paintings hung around. Given that it's Klaus, fatherhood can be the making or breaking of him. But right now, all signs are pointing to Klaus truly looking forward to being a parent together with Hayley.
The season finale is full of these.
Marcel giving Josh Klaus's blood to heal him, when Davina says "Please don't make me choose".
Later, he helps save the baby with the same weapon he was planning to use on Klaus.
In that same episode just about everytime someone holds the baby from Hayley, Marcel to Klaus.
Klaus thanking Marcel for saving his daughter's life and gives Marcel his blood so he can heal from the werewolf bite.
When they realize the baby will be in constant danger by living with them - the give her to Rebekah to take care of. Bonus heartwarming is that one of the reasons Rebekah previously wanted to become human was so she could have children of her own.