User blog comment:American che/Shipping wars-- The reason behind them and how we should be able to prevent them/@comment-1508273-20100310184532

Something I've not seen stated that I feel should be mentioned.

Ferb/Gretchen was initally a sidenote within a fanfiction. The actual fic escapes me at the moment, but the line was something along the lines of "...so I got Gretchen to dance with Ferb so I could be alone with Phineas for a little while..."

This was then amped up within Bottled Feelings, which was a fic which actually sparked off the pairing. After this, it snowballed, and here you have it.