Teen Wolf's Scott McCall needs to "watch his pack" in season 5.

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The supernatural teens of Beacon Hills are headed for a breakdown. About to enter their senior year of high school, the elder members of Scott's (Tyler Posey) squad will be juggling school, college apps, and another batch of deadly threats when the series returns on June 29.

All that pressure is bound to cause some fractures in the tight knit group and it seems Scott and Stiles (Dylan O'Brien) formerly unflappable friendship will be one of the first to crumble.

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"Why can't you trust anyone?" the True Alpha asks Stiles in a new promo (see video below).

"Because you trust everyone!" Stiles snaps back.

Stiles objection to Scott's big heart might have a little something to do with the new lone wolf in town. Featured heavily in the promo below, Theo (Cody Christian) will rub Stiles the wrong way, causing an ill-fated relationship that O'Brien says is tined with hate.

"I can tell you that my character hates him. That's immediately how I felt just now when you even brought his name up. There's a little Stiles in me as well," O'Brien teased at Paley Fest, according to Celebified. "Yeah, I don't like Theo and I feel like there's something up with him...Stiles has eye out for Theo. He's a guy that we used to know growing up and he wants to be a part of Scott's pack. I'm very protective and I don't like him."

Find out what's next for Scott and Stiles when Teen Wolf returns to MTV for a two-night premiere on June 29 and 30.