I've spent way too much time hunting down good stories for this pairing, and honestly the landscape's shifted over the years. Archive of Our Own is absolutely the heavyweight champion now for quality and volume. The tagging system lets you filter out exactly what you want, whether you're after post-canon fix-its, alt-universe AUs, or just pure fluff. The writing there tends to be more polished, and you can find some genuinely novel-length epics that dive deep into the psychic bond thing.
That said, I still have a soft spot for Fanfiction.net's old guard. The classics from the early 2000s have a certain nostalgic charm, even if the formatting is janky. You have to wade through a lot of abandoned WIPs and author's notes from 2004, but gems like 'Reflection' are foundational for the ship. It's worth a cursory search, but AO3 is where the living, breathing community is at now.
For something a little more niche, I've stumbled upon some fantastic, tightly-focused pieces on Dreamwidth communities and personal blogs. The signal-to-noise ratio is higher if you can find an active rec list, but discovery is a pain. My usual method is to find a writer I like on AO3 and see if they've linked to other spots. That's how I found this amazing noir AU on a now-defunct forum, saved only by the Wayback Machine. So yeah, start with AO3, but don't be afraid to dig.