At first, it might be a bit awkward. Teddy has only heard stories about Remus, and Remus is seeing this young man who is his son in a way he never expected. But as they start to talk, they would find common ground in their love for magic and their experiences at Hogwarts.
One possible scenario in this fanfiction could be that Teddy shows some unique magical abilities that remind Remus and Tonks of their own magical heritages. Maybe Teddy can transform in a way that combines both werewolf and metamorphmagus traits, which would be a really interesting plot point. It could also explore how Remus and Tonks, who had such a tragic end in the original story, get to experience some happy moments with their son Teddy through the magic of fanfiction.
Well, it could be about Teddy having a dream where he meets his parents. In the dream, Remus and Tonks are as he's always imagined them. They tell him how proud they are of him, even though they didn't get to see him grow up. This simple encounter could be a very moving and emotional one, with Teddy waking up with a newfound sense of purpose and connection to his parents.
Well, Teddy could learn a great deal about his family's history from the members of the Order. Maybe he'd discover some hidden secrets or untold stories.
Well, it could be about Teddy Lupin traveling back in time and meeting his father's friends, the Marauders. Maybe he gets to experience their pranks first - hand and learns some new magical tricks from them.
Often, the theme of growing up and finding love is present. Teddy is a character who has a lot of growth potential in the fanfic world. His experiences at Hogwarts or in the wizarding world after Hogwarts could lead him to different kinds of love - romantic, platonic, or love for his community. For example, he might fall in love with a classmate who helps him come to terms with his identity, or he could develop a deep love for the wizarding world that shapes his romantic relationships.
The main characters are obviously Teddy, Remus, and Tonks. Teddy is the central figure as he is the one having the encounters. Remus, being Teddy's father, brings his wisdom and werewolf heritage to the story. Tonks, Teddy's mother, with her Metamorphmagus abilities, adds an element of mystery and fun. They all play important roles in shaping the story, whether it's through their relationships with each other or their individual contributions to the wizarding world within the fanfiction.
Well, one possibility is that Teddy, being the son of Remus Lupin, would likely be filled with a sense of justice. He might immediately be on guard around Umbridge. Since Umbridge was known for her cruel and unjust ways at Hogwarts. Teddy could use his Metamorphmagus abilities to play tricks on her, like changing his appearance to something that scares her when she's being particularly mean.