The 18-year-old actor, who portrays Dexter Walker in the Aussie show, told Inside Soap that Dexter's crush on older woman Marilyn Chambers (former Emmerdale actress Emily Symons) made him a source of jokes amongst his friends.
Cottier explained: "It was one of the first things I read about the character, and I was kind of embarrassed, but excited to do it!
"Not every guy comes to Summer Bay and falls in love with a woman 20 years older than him. My friends gave me grief about that! I got to work with Emily Symons though, and she's fantastic."
Commenting on the process of taking over the character from former Home and Away actor Tom Green, Cottier said: "I sometimes hang out with [him] - he's a really nice guy - but I chose not to watch what he'd done. I think Dex is quite a different character now, too."