Some Tommy-centric headcanons while I'm on the bus:
Constantly feels stuck in his brother's shadow. Despite being stellar at customer service, ever being helpful, he believes that Timmy is the true businessman. Timmy, of course, shines inadvertantly - he's just so used to taking charge when his brother needs help that it's second nature now.
This is why Tommy doesn't talk as much when his brother is around.
Nook is aware of this, and has tried time and time again to help boost Tommy's confidence & praise his accomplishments more (because he believes that Tommy is skilled in his sector like Timmy is his own), but Tommy still feels inferior.
Tommy hasn't talked to Timmy about any of this, thinking the issue benign, and that lack of communication just makes everything worse.
Tommy is always as helpful as he can be, but all this insecurity / low self esteem means that he'll go above and beyond for people, even if they don't deserve it.
Tommy is actually a great fisherman! He's caught his fair share of Oarfish and even Sharks, and if there's anyone that knows more about fish out of the twins, it's him.
Where Timmy knows a bunch about technology, hardware details and parts included, Tommy just knows the basics. He's not a huge technology nerd.
