I really like the Sabriel fanfic 'Gabriel's Return'. It has a great story line that involves Gabriel coming back to Sam in a very unexpected way. Regarding Destiel, 'Heavenly Bonds' is a great choice. It goes into detail about the spiritual connection between Dean and Castiel, and how it impacts their actions and decisions in the Supernatural world.
You can start by looking on Archive of Our Own (AO3). It has a vast collection of Supernatural fanfiction, including many great Sabriel and Destiel ones. Just use the search function and type in the relevant tags.
One common theme is the exploration of forbidden love. Both Destiel (Dean and Castiel) and Sabriel (Sam and Gabriel) relationships often go against some sort of 'rules' in the Supernatural world. Another theme is sacrifice. Characters are often willing to sacrifice a great deal for their loved ones in these fanfictions.
One great destiel and sabriel fanfiction is 'The Unlikely Bonds' on Archive of Our Own. It weaves a story where Dean and Castiel's relationship develops alongside Sam and Gabriel's in a really interesting way, with a lot of action and emotional moments.
One common theme is the idea of redemption. Gabriel often has a past full of misdeeds in the Supernatural lore, and in fanfiction, Sam can be the catalyst for his redemption. For example, in many stories, Sam's unwavering belief in the good in Gabriel helps him turn over a new leaf.
Fanfiction.net also has a good number of Sabriel fanfictions. However, the interface might not be as user - friendly as AO3. But it still has some gems if you are willing to dig a bit. Just search for 'Sabriel' in the Supernatural section.
One great Sabriel bar fanfiction is 'The Bar Encounter'. It has a really interesting plot where Sam and Gabriel meet in a bar under strange circumstances. The author does a wonderful job of portraying their initial hesitation and then the gradual attraction.
One common theme is the exploration of their relationship. The pregnancy often serves as a catalyst to deepen the bond between Dean and Castiel. It forces them to communicate more openly and face their feelings for each other.
One great Sabriel fanfic is 'A Hunter's Heart'. It beautifully portrays the relationship between Sam and Gabriel. The story has a lot of emotional depth and some really exciting action scenes that are in line with the Supernatural universe.
Well, it's appealing because it gives a different perspective on their relationship. In the bar setting, there are fewer distractions compared to their normal battles and quests. It allows for a more in - depth exploration of their feelings, like in some fanfics where they have heart - to - heart talks over drinks.