When thinking of Grian, there are two sides of him that everyone always uses.

1) Angsty teen to which he has the most trauma that people dump

2) Charming, confident smack talker

Now I want you to think about a good friend you've spoken to.

Think about their style, the way they talk, every good and bad trait they have.

You see how people are more than just a couple personality traits?

This connects with my OC chapter where you gotta figure out how to really feel the character.

Grian can be rude and snappy, yet he can be caring and loving at times. Overall though, what comes to your mind when thinking of him?

For me, it's his pranks.

Obviously, you can't fit every single personality trait cause it really depends on the story you're writing.

In my prequel to Hogwarts, I have Grian start out as a rude Slytherin but he softens when he falls in love with Scar; I do not, however, include any of his pranking nature (well it's briefly mentioned at the end).

Grian is a very complicated character (along with Etho) and I've honestly hated writing him over the past couple years XD

I've never been able to write him and think "Yeah that's Grian" cause to be honest, I've never found that ground.

Sometimes in my stories he's kind, other times he's rude. Sometimes he's a prankster and teases, other times he's a shy nerd. Sometimes he's a survivor and throws others out of the way, and other times he's growing while lifting others around him.

Every Grian across all of my stories are different.

And you know what? Across every series, he's different.

3rd Life he tends to be caring towards Scar, despite being a little bit defeated. He looks out for him and he actually ends up crying at the end when Scar dies.

Last Life, he does pranks with Mumbo before going a bit insane and turning to be a bit insane with the "We can still be friends. You can join me" and he tries to kill Mumbo.

Double Life, he just cares about himself and his survival. The only reason why he sticks around Scar is so he won't die; but we also see him being soft and kind towards Big B.

Limited Life he looks out for The Bad Boys while doing pranks, and the angst with him losing them is crushing.

Across all of these series and more he's never the same! And that's extremely difficult.

The best thing I've found to do is try and find the personality you like and prefer to write and stick with it.

As mentioned earlier, the AU weighs into this heavily.

In my high school AU's he tends to be like he is in Limited Life. Pranks, teases, yet he cares deeply for his friends that he almost sees as family.

In any superhero/Cute Guy AU I have him be his Last and Double life self. Rude and secretive, yet he has a bit of a soft spot.

Overall, it's just a style choice. My best recommendation would to make sure not to destroy him completely.

The problem I see in a lot of stories, not just Grian related, is that with the angst it tends to break down the character.

We dump so much trauma that their fun traits get forgotten and we just hammer down the sadness.

Just remember they're more than characters, and picturing them like people can help to try and make it more realistic.

Good luck :D!