In the first two episodes Beatrix wears a robe to conceal her identity. When she unleashes the Burned One that was chained in the barn. The robe gives her a very witch like appearance which makes perfect sense because she was born in Aster Dell and the settlers of Aster Dell were Blood Witches.
Beatrix is an air fairy, and Farah mentions Tinkerbell was also an air fairy. Now, what role did Tinkerbell have in a previous Winx show?
Stella considering Bloom her friend does seem out of nowhere and out of the blue near the end of the first season. However, some early clues hint at her eventual turnaround:
As explained with the novel adaptation, Stella dislikes Bloom mostly for being the "girl of Sky's dreams". Stella is highly under pressure from her mother and given Sky is the only one she knows to genuinely like her, for the newbie to take him away, it gets her miffed. She noticeably only acts directly antagonistic towards Bloom when it comes to Sky, otherwise is just as mean to her as everyone else.
Riven says Bloom reminds him of Ricki, Stella's former best friend. Given the guilt of having blinded her by accident, Stella would normally not want anyone who reminds her of Ricki if Bloom's similar to her. She's literally afraid of becoming Bloom's friend and having to redo that process when Bloom also obviously likes Sky. Sky's also no longer an issue or a source of problem once he and Stella finally break up. In other words, she pushes Bloom away because she knows Bloom is exactly the kind of friend she wishes she had.
In the second episode, Stella angers Bloom into successfully summoning her powers. Despite being harsh about it, once you learn the utter abuse Stella went through, it seems less like Stella's provoking her and more like she's helping her use her powers the best way she knows. Note she doesn't do this for any other character and could leave Bloom in jeopardy while inside the forest, but still makes the effort for Bloom. Regardless of her attitude, part of her is already concerned about Bloom, even if she won't admit it.
Stella puts up a nice act in public by acting classy with other students, but shows a harsher side to her suitemates and boyfriend. One of Stella's fears in the beginning of the show was the other girls hating her. There's also how she ghosted Sky for the summer, and her mother's tough brand of educating her not giving her a bright idea of how a healhy relationship works. It seems Stella only acts harsh to those she feels somewhat close to, meaning she already considers the Winx people she can call close, even without realizing it.
It also helps that Terra has expressed missing Stella during the latter half of the first season and Musa even tells Stella her fears are unfounded. With acceptance and positive interactions with people she actually knows and who know her for who she is, Stella no longer needs to shield herself and can finally act nicer without putting up a front to appear strong. Had she not been forced to act that way, it's likely she'd be much closer to her cartoon counterpart in personality.
Why is Riven especially hard on Musa when she initially wants to be a Specialist? Well, he saw her face the Scraper and essentially give up her magic, which gave Sebastian more power, so he knows that she did end up giving them an even trickier enemy to fight against.
Riven and Sky especially have shorter and tighter haircuts in Season 2 than Season 1, coinciding with Andreas and Rosalind being in charge and turning the academy into more of a military academy. The Specialists are essentially military themselves, and most armies have regulations about keeping hair short and neat. While theirs is longer than most military haircuts (which are usually high and tight), it matches the hairstyle Andreas has. Maybe his is the regulation in their universe? Silva by contrast keeps his a little longer even after coming out of confinement; showing that he's not as strict or mercenary as Andreas.
Queen Luna uses Aisha not knowing that Grey was a mole as an example of why she's a Horrible Judge of Character (and therefore can't vouch for Bloom). Except Grey's feelings for Aisha were genuine, he had sympathetic reasons for being a mole, and he ultimately had a Heel–Face Turn. So Aisha is a good judge of character after all.
Musa demonstrated better combat technique against Riven in Season 1 than when she actually first tries to be a Specialist in Season 2. First of all, she still had her powers in Season 1, and so she could likely sense some intention behind what his next move would be and block that. Secondly, she's suddenly having to adjust to not being able to hear other people's emotions, so her co-ordination is bound to be off. Thirdly, Riven was likely holding back the first time, assuming she was weaker, whereas this time he knows what she's capable of (and she actually tells him not to go easy on her).
Beatrix says she won't forgive Sky for killing Andreas, but she still saves him the finale. She demonstrates the very lesson she taught Stella; put the needs of the many before her own desires. Bloom was giving up the Dragon Flame to save Sky, which would give Sebastian what he needed to open the portal. So saving Sky stopped Bloom from giving Sebastian more power, even if Beatrix didn't care about him. She possibly also felt that if Stella joined the battle, she'd fight better knowing Sky was safe and didn't have to worry about him.
