I feel like in order to understand Tim Stoker as a character you need to know two things about him:
I just think that if you forget these things you're forgetting some important pillars of his character
he has so much love in his heart and that's what fuels a lot of his anger in the series. he's angry because he's losing the people he loves, either by death or emotional distance, and he's so angry that he can't do anything to fix it. angry that they're all stuck. he's so sad, grieving people and friendships, and that manifests in his anger.
Danny is, of course, also essential to Tim's character. that's his baby brother. his "cool little brother". this is a man tim admires and is proud of, despite having several reasons to be envious of him. he loves him so much and what happened to Danny destroyed him irreparably. he called himself a coward because he was too afraid to move when he saw "Danny" on that stage in covent garden theatre. I don't recall him ever freezing up like that after that instance. he did everything in his power to protect the people he loved. he broke down a wall during the prentiss incident, he followed jon back into the archives when he knew something was up, he followed Martin into the tunnels when he was going to go down there alone.
his love and him being an older brother are So essential to his character, and I wish people would recognize that more and not reduce him to the flirty funnyman slacker