You need a good wing-man...
Sticking to the theory that writing is like dating, I'm thinking about having a kick-ass "wing-man". What's a wing-man? Traditionally, a single guy/girl goes in search of potential dates...but never alone. That would be boring!(and dangerous)
A solid wing-man(wing-woman?) pumps you up and helps you maintain an even balance throughout the night. They offer up levity, when necessary. They offer advice (good or bad - depends) when advice is needed. If they are a good wing-man, they will redirect you if you steer off course. Ultimately, they assist in reaching the night's goal. (Whatever that might be)
This is true for secondary characters in your novel. Take Mela's best friend and "wing-man", Wyatt. Yes, her best friend is male and that says a lot about her. However, he is gay, so there are no romantic entanglements to worry about. The fact that he is gay serves a purpose for both the story and for Mela. 1.) The aforementioned romantic complications are not there. He can advise her and be there for her without the reader blurring the relationship in their mind. 2.) He is objective and can identify with her, personally, but is a strong man in his own right.
Wyatt lays out the truth for Mela - because let's face it - Mela is flawed. Like, really flawed. She has her reasons, and they're good ones. However, Wyatt can see where she has allowed her flaws to become a crippling weakness. A weakness that the protagonist could exploit.
In another novel, Wyatt could stand on his own. He is not there just to drop information or for comedic relief. He is, at the beginning of the series, more together than Mela is! Emotionally that is. He has a rich past and opinions/hangups of his own. Yes, he's hilarious at times. But he's an anchor too. He is essential! He is the perfect wing-man for Mela.
A sloppy wing-man can get you into trouble. When choosing your wing-man (secondary character) really, really consider what he/she has to offer. Is it just to be silly and get laughs? The goofy wing-man attracts more attention, yes, but everyone is looking at him and not you.
A boring wing-man can have the same, if not worse, effect. If he/she just lurks in the background - totally useless - Why bring them out with you? Your energy will be brought down by the boring wing-man and then all you'll attract are the drunk and desperate. (Bleh)
Having you and your wing-man in sync is essential. (Your main character and the secondary character(s)) What's the night's plan? Does he have your back? Do you have his? Are you a team? Asking myself this about Wyatt, I was forced to answer the question- Is there a purpose for him in the story other than laughs/info dumps/eye candy?
Yes. As I said, he can stand on his own in another story. But the relationship between he and Mela is also essential. A win all the way around. He is smart, funny and caring. He props her up where she lacks - she needs him. Wyatt aids her in her foray into the world of witchcraft and danger. Sometimes he gives information, sometimes he gives a supportive hug, sometimes he calls her out on her B.S. Sometimes, he is the one that needs the hug. I am able to show her vulnerable side through him as well as her strengths.
Could I tell the story without him? Maybe. But it wouldn't be as much fun for me, or for Mela. They are a great team. He is her wing-man through all five books. Their relationship gets tested at times and he needs saving occasionally, but overall...he was the BEST choice for her. Not the only one, but the best one.