Well, the Thunderbird can be a great help in his adventures. It can assist him in exploring new places, as it can cover large distances quickly. Also, it might attract the attention of other magical creatures, which could lead to new friendships or alliances for Harry.
Yes. In many fanfictions, Harry's Thunderbird familiar often has special abilities. For example, it can fly extremely fast, which helps Harry in situations like quickly delivering messages or escaping from danger. It might also have the power to sense approaching storms or other natural phenomena, giving Harry a sort of early warning system.
Their relationship could be one of mutual respect. Harry would respect the thunderbird's instincts and power, and the thunderbird would respect Harry's leadership and magical abilities. They would rely on each other in difficult situations. For instance, in a battle against Voldemort's followers, the thunderbird might listen to Harry's commands to use its abilities in the most effective way.
If Harry's animagus form is a large and powerful creature like a dragon, his familiar might be in awe of him. It could lead to a relationship where the familiar is very submissive and looks up to Harry for protection. For example, the familiar might be a little imp that hides behind Harry when they encounter other dangerous magical beings.
It could interact in a protective way. For instance, when faced with a group of imps causing trouble, the Thunderbird might use its storm - creating ability to scare them off and protect other magical creatures like the unicorn that are more gentle and vulnerable.
If the familiar is something like a dragon, it could greatly impact the plot. Dragons are powerful and feared. The character with the dragon familiar might be constantly hunted by those who want to use the dragon for their own purposes or those who fear its power. This would create a lot of conflict and drive the story forward as the character has to protect their dragon and themselves.
The dark familiar can make Harry more cautious. For example, if it has a tendency to attract dark magic or dangerous situations, Harry has to be more aware of his surroundings. This forces him to grow in his ability to sense trouble.
Some characters might be afraid of the snake, like Neville. This could cause some tension between Harry and Neville at first. But as they get to know the snake better, their relationship could improve. Hermione might be initially skeptical, thinking it's a bad idea to have a snake as a familiar. However, she could come around when she sees how useful the snake is. Ron, on the other hand, might be a bit jealous that Harry has such a cool and unique familiar.
It would make their life at Hogwarts very special. For example, they might be able to use the unicorn's speed to get to classes faster. Just imagine zooming across the Hogwarts grounds on a unicorn instead of walking.
The demon wolf familiar could make Harry more confident. Since he has this unique and powerful companion, he feels more capable of taking on challenges. For example, when facing bullies like Draco Malfoy, the presence of the wolf gives Harry an extra sense of security, which in turn makes him stand up for himself more often.
Well, in some fanfictions, a Thunderbird as a familiar might be the key to unlocking an ancient magic. For example, the wizard has to bond deeply with the Thunderbird to access a powerful spell that was lost for centuries. The Thunderbird's majestic presence and its connection to the sky elements make it a really cool and powerful familiar in these stories.