The pair have been getting along well while launching a deli business together this year, but viewers recently saw that Doug was starting to regard Ste as more than just a friend.
Brennan, discussing the storyline for the first time, told All About Soap: "He doesn't really understand where these feelings for Ste have come from - they're completely alien to him. All Doug knows is that it's very strong and real. This is not a gay storyline - it's exploring sexuality in general."
Doug finally confesses his feelings to Ste next month, but it's clear that he is still unsure about what he wants.
Brennan continued: "Doug tries to take back his feelings, because he thinks that's what Ste wants. But Ste is also coming to the realisation that he may feel the same way about Doug. It leads to a big argument and they end up sharing one of those, 'Oh shut up' kisses. You definitely can't take that back!
Asked whether Doug is ready for a relationship with a man, he replied: "No, I think there's a lot that needs to be worked out first. Over the next few weeks, viewers will see him trying to get to grips with what's happened. Doug is quite hard on himself, so this is going to be a huge journey for him. He's about to be forced to work out exactly what it is that he wants."
Brennan also warned that there will be "trouble for everyone" when Ste's ex-lover Brendan Brady (Emmett Scanlan) inevitably finds out about the surprising developments.
Hollyoaks airs weeknights at 6.30pm on Channel 4 with a first look screening at 7pm on E4.
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