Well, 'Castiel and the Elements of Harmony' is also worth checking out. In this fanfiction, Castiel gets involved with the powerful Elements of Harmony in the MLP universe. His angelic powers and knowledge play a big role as he teams up with the ponies to face a common threat. It's a great read for fans of both Supernatural and MLP as it blends the two universes so well.
One popular piece of fanfiction might be 'Castiel in Equestria' which combines the two universes in an interesting way. It has Castiel interacting with the ponies from MLP in a world filled with both magic and the unknown, much like his experiences in Supernatural.
Well, 'The Angel and the Hunter' is a popular Castiel Supernatural fanfiction. It delves deep into the relationship between Castiel and Dean. It shows how their bond develops over different situations and challenges they face. Also, 'Castiel's New Powers' is quite exciting as it explores Castiel getting some new and unexpected powers and how he copes with them.
One great Castiel fanfiction is 'The Road So Far'. It delves deep into Castiel's internal struggles as he tries to understand his place among the Winchesters. Another is 'Wings of Redemption' which focuses on Castiel's journey to regain his grace and his relationships in the process. There's also 'Castiel's Quest' that takes the character on an adventure to save Heaven while dealing with his loyalty to the brothers.
I really liked 'In the Shadows with Meg and Castiel'. It's a more introspective piece that explores their individual struggles and how they come to rely on each other. The descriptions in the fanfiction are really vivid, making you feel like you're right there in the Supernatural universe with them.
There's also 'Castiel's Redemption'. This fanfic focuses on Castiel's journey of self - discovery. It shows his interactions with the other characters from Supernatural and Ghostfacers in a very engaging manner. It's full of emotional moments and great character development.
The character of Castiel in these fanfictions often has to adapt to the MLP world. His interactions with the ponies, who are so different from the humans and angels he's used to in Supernatural, are full of humor and unexpected moments. For example, he might be confused by their simple ways of solving problems through friendship, which is a very different concept from what he's used to in his own world.
One common theme is the clash of different worlds. Castiel, from the dark and often gritty world of Supernatural, finds himself in the bright and magical world of MLP. This contrast often leads to themes of adaptation and understanding.
One great 'castiel x dean supernatural fanfiction' is 'AUs Are Made of This'. It has a really interesting alternate universe concept where their relationship develops in a unique setting. Another is 'Heaven Can't Wait' which delves deep into their emotional connection.
One great 'Supernatural Castiel sad fanfiction' is 'Fallen'. It delves deep into Castiel's internal struggles after a major fall from grace. Another is 'Alone', which shows Castiel feeling isolated and sad due to his unique position among the angels and his relationship with the Winchesters. There's also 'Lost Hope' that focuses on a time when Castiel loses his faith in the mission he once held so dear.
One great 'Supernatural Castiel Abandoned' fanfiction is 'Abandoned by Heaven' on Fanfiction.net. It delves deep into Castiel's feelings of isolation after being seemingly abandoned by the angels. The story is well - written, with great character development.