I would say love at first punch, but I'm fully convinced Lockdown had the hots for Prowl the minute the motorcycle snuck up and revved him full on the face in "The Thrill of the Hunt".
There actually was a small scene that got deleted where Lockdown would be spying on Prowl from his home, only for Prowl to get suspicious. I had to cut it for pacing issues.
This reminds me of a bionicle joke:
"Ah! Don't sneak up on me!"
"Says the Toa wearing the mask of stealth."