Basically Lucario and Mystery of Mew happens but Ash and Lucario are way better companions than Lucario was with Sir Aaron.
Lucario is magically brought back to life whether it be via heaven or something more spiritual lyrical cynical pinnacl-
Lucario loves Ash (You guessed it) and sets out on a journey to find his love because Ash doesn't know he's alive.
Obligatory MiStY iS jEaLoUs REEEEE-
Ash loves him back (You fucking guessed it) and refuses to believe that Lucario is dead and also May is jealous, also Ash doesn't know he's fucking alive-Ash and Lucario find each other and fuck...
checks watch
They collapse in bed together and Lucario gets pregnant because... um...
fuck