In an interview, the cheeky youngster and native Bavarian expressed his appreciation of Dortmund and delight in causing trouble for his hometown's most successful club
Speaking with Bild, the 19-year-old pledged allegiance to his club, claiming a certain magic about the Signal-Iduna Park's famous south stand.
"I am really pleased about each appearance. Because I play for the hottest club I can think of," he said. "Anyone who has stood in the Sudtribune gets the black-and-yellow fever."
The Munich native, who played for 1860 from 1998-2011, also weighed in on the growing war of words between Dortmund and Bayern.
"It's always nice to annoy Bayern, whether as an ex-Lion [1860 player] or Dortmunder."
Leitner is especially looking forward to making an impression in the coming weeks as he is tipped to start in place of injured defensive midfielder Sven Bender.
Ahead of Saturday's match against Bayer Leverkusen, the Germany Under-21 international revealed that he will call upon wisdom passed on by coach Jurgen Klopp before his Bundesliga debut earlier this season.
"A phrase I have not forgotten: I should play the way I look - cocky."
Kick-off in Dortmund is scheduled for 15.30CET.