Chloe Hartman (crush)
- The Danger Begins
- Tears of the Jolly Beetle
- Jasper Danger
- Birthday Girl Down
- Too Much Game
- Henry the Man-Beast
- Henry and the Bad Girl, Part 1
- Henry and the Bad Girl, Part 2
- Jasper's Real Girlfriend
He is clear-thinking and logical, yet quirky. However, he is less quirky than his best friend Oliver Pook but has a silly-side when he's with him.
Relationships With Other Characters
He and Oliver are best friends. Sidney dresses Oliver every morning.
- After Henry the Man-Beast, he was absent for 12 episodes. He returned in Henry & the Bad Girl: Part 1.
- He may have stopped eating bugs, as shown in Birthday Girl Down.
- It is revealed that Sidney may be Jewish. He might celebrate Passover.
- In Birthday Girl Down, Ray draws an intersex gender symbol next to Sidney's name on the suspects board instead of a male gender symbol, showing that some characters may see him as being androgynous or not completely male.
| To view the Sidney Birnbaum gallery, click here.