Alright, diving into the Arshi fanfiction rabbit hole is basically my favorite pastime. For long-form, intricate stories, FanFiction.net still has the classics that everyone recommends, but the tagging system is a nightmare. That's why I practically live on Archive of Our Own now. The filters are a godsend for finding specific tropes like arranged marriage AUs or post-'Jahan Jale Yaara' reunions.
Don't sleep on dedicated forums and groups, though. There's a huge community on Facebook—search for 'Arshi Fanfiction' or 'Arhi' and you'll find groups where writers post directly. The interaction there is more immediate, and you can sometimes find amazing WIPs that haven't migrated to the bigger archives yet. Wattpad has a massive amount, but quality varies wildly; I sort by 'completed' and 'most reads' to sift through it.
My personal strategy? I keep a running list on a Google Doc of fics I love, with links. It's saved me so many times when I want to re-read something but can't remember the name. The best ones, for me, are always the ones that capture Arnav's sharp edges and Khushi's stubborn warmth without making them caricatures.