Early Life

Cobrakit was born second in a litter of three, alongside the firstborn son Eaglekit and his sister Lightkit.
He was a wild tom, always urging his siblings to play and asking his parents questions about anything that entered his mind. Due to his father Finchstar's many duties, he spent most of his time with his brother, sister and mother, Suntail, and quickly became quite the troublemaker.
However, the happiness was quick to fade.
Unbeknowenst to Finchstar, their mother had carried a disease that took hold within the kits' second moon. Cobraheart was not as strong as his brother, but still able to handle it better than his sister Lightkit. Within the moon, life had completely left her and while Eaglekit stayed by his dying sister's side, Cobrakit would wheeze in his nest, trying to shut out the sadness and anger that rushed through his body. Sure, she would go to StarClan - but how did that help Cobrakit? She was still gone!
Finchstar didn't exactly help any of them deal with Lightkit's death, unleashing his angers on his mate who herself had become grief-struck and submissive, following her only daughters demise.

Apprenticeship

With his father's leadership and training, Cobrapaw had already adapted his attitude of superiority to anyone else - especially she-cats, who just couldn't do anything right.
While Eaglepaw's reserved and watchful demeaner helped him adapt to whatever it was Finchstar wanted, Cobrapaw seemed to hit walls wherever he turned. First he was too reckless, then came too mouthy, too angry, too opinionated, too questioning...just too little like his father. Finchstar would come up with new ways to punish his sons every time one of them screwed up, which would usually end up being Cobrapaw. While Eaglepaw caught on quickly and learned to act his way through his father's wishes and how him exactly what it was he wanted, Cobrapaw for a long time refused to just play the good son, no matter how many nights he was forced to stay awake to 'listen to his mistakes', as his father called it.
With every mistake, every emotion being made out to be a shame, unforgiveable in nature and unworthy of the leader title, Cobrapaw would give his everything to avoid making them. He surpressed all his anger, all his bitterness and sadness to smoothen the path to his father and trained as hard as physically possible to succeed at everything that was asked of him.

Being leader was his highest goal - to succed his father and better him, to be respected and valued by the clan, keeping them safe and strong, to have a family with a mate that supported him like Suntail would always support Finchstar in whatever he said or did and, of course, to have and train the bravest, smartest kits of them all. The perfect family. A family his father would be proud of.
Of course, everything that stood in his way...would have to be removed.

Becoming Cobraheart

By the time he was ripe to become a warrior, his attitude and personality seemed to have changed completely.
In front of the clan, Cobrapaw and his brother were the perfect sons to Finchstar, respectful, hardworking, honest and loyal, always fighting for the clan, their father and of course each other, all the while entertaining a healthy rivalry.
Now of course, everything was a lie.
The relationship with his father was distant at best, the opposite of honest and despite the anger Cobrapaw harbored against his father, he was still seeking to raise his reputation with his father and clanmates - after all, not only Finchstar and deputy Martenpelt would be the ones to choose the next leader, as general likeableness within the clan counted almost as much.
His brother Eaglepaw had long seazed their somewhat close relationship, it wasn't as much a healthy rivalry as it was a private deathmatch between the two, as both of them wanted nothing more than to be leader, but knew the other one would do whatever they could to stop them. And so they never talked honestly with each other, except when they were making fun of clanmates they both thought to be worthless or simply too problematic. In those rare moment where it always seems like they are brothers again, Cobrapaw finds himself thinking back to how they used to play together as kits, though barely remembering their sister as a personality, but more as something that was taken from him.

But the biggest lie was Cobrapaw himself. All the faking of emotions and surpressing of others had led to him just being simply unable to cope with what he was feeling. Already being quite an emotional tom, Cobrapaw developed a severe anger problem that would slowly swell up through time and then cause him to snap when provoked enough, flying into rages he couldn't almost remember in their entirety. When Cobrapaw lost control like that, it was entirely possible for him to do things he would later come to regret, but still justify his behaviour to himself to keep the guilt away like he does everything else.
He's not honest, calm, collected, respecting of everyone from senior warrior down to the apprentices, patient or any of the things he pretends to be for his clan. Instead he's hotheaded, sarcastic, arrogant, he enjoys fighting and using his privileges to get his way and values she-cats and their duties about as much as one would value the dirt between one's claws. When it was time to become a warrior, he was given the name Cobraheart for his bravery and loyalty, two characteristics he embodied to a fault and the only part of himself he didn't have to carefully act to please his father.

Of course, in the same breath, he took Mintpaw as his mate - a rebellious, mouthy she-cat well-known for despising Cobraheart and his brother, but also to be the only friend of Spiderpaw, another apprentice and a tom Cobraheart found absolutely repulsive. Becoming mates with his one friend in the clan combined with Eaglepaw, who had now become Eagleshade, choosing Rowanpaw as his mate, who was Spiderpaw's sister, he felt like he had enacted the perfect little revenge on the scrawny disappointment of a tom. Maybe he would even leave the clan?
Of course Mintpaw was disgusted by what he did and vowed to not only never have his kits, but to fight him every step of the way for what he did to her and Spiderpaw, which greatly angered Cobraheart but also left him no possible path of action - she had just become his mate after all, he could harm her now, could he?
But still, Cobraheart was satisfied by the pain he had caused and since he was now a warrior, he had come a big step closer to becoming leader.