Monty Monogram and Vanessa Doofenshmirtz have romantic feelings for one another, despite their warring fathers. As a result, they keep their relationship secret from their parents, usually with Agent P helping them hide from their fathers.
Monty's Feelings for Vanessa
Monty has feelings for Vanessa. He first sees her after flying off her father's roof, giving her a slight smile before he returns to the O.W.C.A. building ("Minor Monogram"). He meets her again at the Steam Noir and they share a drink together. Although they eventually have an argument over their fathers, they decide to meet again ("Sipping with the Enemy"). He goes with her to the Doo Wop Hop and is spotted by Carl, but his father does not find out ("My Sweet Ride"). He then went out with Vanessa to the Steam Noir again. ("Thanks But No Thanks") Then he went to her costume party and danced with her as the Scarlet Pimpernel. ("Druselsteinoween")
Monty is keeping his relationship secret from his father due to Vanessa's dad being an evil scientist.
Vanessa's Feelings for Monty
Monty is Vanessa's love interest after her breakup with Johnny. When Vanessa first sees Monty, she states that she might try to date a "good guy" for once ("Minor Monogram"). They later meet at the Steam Noir and share a drink. Although they eventually have an argument over their fathers, they make up ("Sipping with the Enemy"). They later go together to the Doo Wop Hop and narrowly avoid being noticed by her father ("My Sweet Ride"). They later went to the Steam Noir again. ("Thanks But No Thanks") Then she invited Monty to her costume party and they danced together as she dressed as a vampire queen. ("Druselsteinoween")
Like Monty, Vanessa is hiding her relationship hidden due to Monty's parentage. However, she has used Perry to hide it, which has worked effectively ("Sipping with the Enemy").
However, considering that in the episode "Act Your Age", set ten years after the main series, Vanessa is engaged to Ferb Fletcher, it suggests that Vanessa and Monty have broken their relationship during that gap of ten years.
|The image gallery for Monty and Vanessa's relationship may be viewed here.|