Robert Sheehan intends to make the mundane magical in the big-screen adaptation of Cassandra Clare's "Mortal Instruments," set for an August 23 release.

The film centers around Brooklyn teen Clary Fray (Lily Collins), who discovers after her mother's kidnapping that her family descends from a long line of Shadowhunters, a half-human, half-angel race tasked with ridding the world of dangerous demons. When Clary takes up with Shadowhunter Jace Wayland (Jamie Campbell Bower) and the rest of his clan to rescue her mother, best friend Simon (Sheehan) is left the odd man out — quite literally.

"Simon, he's the only normal guy in the whole script in the sense that everyone else has some kind of magical ability, so he's very much the normal perspective, the normal eyes, the guy who is kind of asking the questions," Sheehan told MTV News' Josh Horowitz during a visit to the Toronto set last year. "He's thrust into these very abnormal situations. It's quite exciting."

Yet, for all the supernatural shenanigans that transpire, Simon also faces a very real teen problem: unrequited love.

"It's very clear from the beginning of the story that Simon is quite desperately in love with his friend, who's been his best friend pretty much all their lives," Sheehan explained of his character's affections for Clary. "And it eventually comes to the fore, and they kind of work through it. It's interestingly written in the script because it's kind of just about small conversations that happen between two friends and eventually ends up in, 'Hey, by the way...' And it's been a lovely part, and I'm working with that amateur Lily Collins, and I'm dragging her through the dramatic stuff, you know."

And while the leather-clad, weapon-wielding Shadowhunters (which also include Kevin Zegers and Jemima West) are arguably much hipper than nerdy Simon, Sheehan says he doesn't envy his Nephilim-portraying counterparts.

"They may look cool in their leather and sexy boots, but they have to come in about two hours before I do every day to get those rune tattoos put on and taken off and put on and taken off, so they get a lot less sleep than I do."

Check out everything we've got on "The Mortal Instruments: City of Bones."