Robert Brown|A Project Runway All-Star Hits on Mentor Christian Siriano in Flirty Season 20 Preview

Flirting is Robert Brownin fashion on Project Runway.

In E! News' exclusive sneak peek at the Bravo series' season 20 All-Stars premiere, one of the returning designers shoots his shot with mentor Christian Siriano during a workroom check-in.

The contestant in question? Season 17's Bishme Cromartie, who Christian tells in the preview, "I'm glad you're here."

The moment is bittersweet for Bishme, who wants to do well in the challenge to honor his late sister. "I have a clear vision of my brand and how I want it to be, so I'm just back to do that," he says of his latest creation. "And also for my sister."

Christian senses Bishme's somber mood. "You sure you're alright?" the season four winner asks him. "Do you need anything from me?"

Changing the melancholy mood in the room, Bishme cheekily replies, "A kiss would probably help," before Christian offers, "Like a hug?"

Bishme responds, "I said a kiss, not a hug." The two share a sweet embrace as Christian jokes, "A kiss next week."

The teaser also shows Christian having a sweet reunion with his fellow season four alum Rami Kashou, who is back for another shot at the $250,000 prize.

"Isn't it so nice to see each other?" Christian asks Rami, who replies, "It's bizarre."

In his confessional, Rami explains how he really feels about following Christian's guide 15 years after they last competed against each other.

"During Project Runway season four, I mean I lived with Christian," he notes. "We went through the whole journey together. We got to bond over the stress of the competition."

See the sweet sneak peek above, and keep reading to meet all the returning season 20 all-stars. Project Runway's two-part premiere airs Thursday, June 15, at 8 p.m. on Bravo.

(E! and Bravo are both part of the NBCUniversal family)