Nico Robin is the archaeologist of the Straw Hats and one of the main characters in One Piece. She had one of the more interesting stories out of the members Luffy recruited into the crew, and was directly opposed to the crew for some time.
She's also one of the only members who actually invited herself into the group. She started off as mysterious and secretive, but she's opened up to her new family and shown different sides of herself over time. While she's undergone many changes since she appeared in Alabasta, there's still plenty of things about Nico Robin that have wonderfully stayed the same.
10 CHANGED: From Villain To Ally
When Nico Robin was first introduced, she was the right hand of Crocodile and a member of Baroque Works. She and her group were the main antagonists of the Alabasta arc and actively opposed the Straw Hats. However, she saved Luffy a couple of times throughout the arc, showing that she wasn't all bad. Eventually, after Luffy in turn gave her the will to keep living, she snuck aboard their ship and joined the crew. She's now a treasured member of the Straw Hats.
9 SAME: Intelligent
From her very first scene where she was toying with the Straw Hats, it was clear that Robin was incredibly intelligent. This was further proven as her backstory was revealed, showing that she grew up among scholars and did plenty of learning on her own. She is still one of the smartest Straw Hats, and is the only known person in One Piece who can read the ancient writing of the Poneglyphs. Even in battle, she is shown making smart and tactical decisions rather than just diving in headfirst.
8 CHANGED: Physical Appearance
Like many of the Straw Hats, Nico Robin's appearance changed significantly after the timeskip. She transitioned from being thin to having more of an hourglass figure, as well as her dark skin becoming much more fair.
Her shoulder-length straight hair also changed, growing further down her back and becoming wavy. While not super obvious, her nose has also lost a lot of the definition that it had before the timeskip. She's barely recognizable as the same person now.
7 SAME: Dark Humor
Even from the beginning, Nico Robin was prone to saying some pretty dark stuff. If they aren't sure where a few of the other Straw Hats have gone, she's quick to assume they've died in some gruesome way. She once assumed that they had been strangled after being unable to hear their voices for a while. While she doesn't smile or laugh when she says these things, it's unlikely that she truly believes that these events have occurred. She also only says them near other Straw Hats, who tend to react pretty strongly to the suggestions.
6 CHANGED: Much Stronger
Nico Robin was no slouch before the timeskip, but like the other Straw Hats, she did grow stronger over those two years. She specializes in submission moves, and she was excellent at them throughout the entire show. However, she didn't have a way to handle stronger or larger enemies until afterward. She can now sprout a million arms or legs at once to create giant limbs that she can use to attack stronger foes. She's now easily one of the stronger Straw Hats.
5 SAME: Reserved And Calm
Unlike most of the other Straw Hats, Nico Robin doesn't openly display what she's feeling. Whereas the others will have comical or exaggerated reactions to events, Robin will take them in stride. There have been very few occasions where she displayed her emotions openly, and these have been in extreme situations like at Enies Lobby or when confronted by the Marine Admirals. Otherwise, she will just portray her calm and neutral expression, with the occasional smile or giggle.
4 CHANGED: Trusting Her Crew
Nico Robin has been hunted by the World Government since she was eight, so she knows that she's in constant danger. She joined with the Straw Hats for a while before leaving them at Enies Lobby. She did this to protect them, as the people that captured her threatened to destroy them.
After the Straw Hats grouped together and rescued her, she is now more comfortable and trusting of them. She knows they will protect her and that they are strong enough that she doesn't need to leave to protect them.
3 SAME: Love For History
While she was studying on Ohara, Nico Robin gained a love and respect for history that has continued throughout the whole series. She takes every chance she can to study ancient ruins and old texts, especially when the Straw Hats were on Skypiea. In one of the few moments that viewers see her truly angry, she had to handle Yama while he was destroying these ruins. She drew him away before viciously defeating him, making sure he knew just how much of a sin he had committed before killing him.
2 CHANGED: Relationship With Aokiji
Nico Robin and the Admiral Aokiji have had an interesting history together. He was there when her home was completely destroyed by the World Government, but went against orders and ensured that she escaped. She then lived for 20 years in constant fear of him, dreading the day he comes for her. Once he did, she was petrified and had to be saved by her crew who almost died. After Enies Lobby, Aokiji proves that he wants her to be free and live on, even going so far as to cover up their presence. They are now at the bare minimum amicable towards each other.
1 SAME: Mischievous
While Nico Robin tends to be serious and aloof, she does have a mischievous side. It began when she was a child on Ohara, where the other kids bullied her for having Devil fruit abilities. She would then use these abilities to mess with and tease them but never cause any harm. Recently she did a similar thing to Chopper, using her power to hold his arms wide before tickling him. This is a more innocent and childish side to Robin that it seems she hasn't lost throughout her life.