The two sides meet in another west London derby on Saturday at Griffin Park with only two points separating them, although Slavisa Jokanovic's side are unbeaten in their previous two meetings with Dean Smith's men.
Fredericks spent time on loan at the Bees in August 2012 when he signed from Tottenham, but was recalled by his parent side in October having made just five appearances.
It was the 25-year-old's first real taste of men's football, and Fredericks believes the time he spent in TW8 was a good learning curve for his career and helped him become the player he is today.
He said: "It was a first ever taste of men's football, it was a good introduction into how far I actually was from being an established a first team member from what I thought I was.
"When I went there I thought 'oh I'd fit in easily' but that wasn't the case, it was a good learning curve for me.
"I went there and it showed what I needed to work on and over the next couple of years I went back and worked on my training."
Brentford finished that season in third place in League One, missing out on promotion to Doncaster and Bournemouth courtesy of a missed Marcello Trotta penalty before being beaten by Yeovil in the Play-off final, and Fredericks has paid the team credit for the way they've dragged themselves to be an established Championship side.
When asked if he was surprised at how well they'd done in recent years, he said: "Yes and no really, there's always potential there because they play the right way - even back in the day when I was there they tried to play the right way.
"Every year they seem to lose their best players but keep on producing new players and finding new players so all credit to them to be fair, they've done really well."