Alice or Bob's parents expect them to inspire people and have perpetually good attitudes, so they do, to please Mom and Dad.
Alice or Bob got the disability in an unusually inspiring way, such as through being a Marine and saving a buddy from a car bomb.
Alice is actually quite cynical and sharp-tongued, but her friends rely on her insight and honesty no less for that.
Bob's not great on the sports field, but he has a sense of humor about it, and puts everyone at ease around him.
When we first meet Alice, she's full of smiles and tugs at your heartstrings — because she's ten. When we fast-forward to her life six years later, she's going through adolescence like any other girl.
Charlie's mom wants her son, the local jock, to like and befriend Bob, so she tells Charlie that Bob is a stellar athlete "in spite of his handicap." Bob turns out to be an average-caliber athlete, and remarks that he hates it when people exaggerate his skills.
Alice or Bob respond to remarks about their inspiration with Deadpan Snarker attitudes.
... after her tumultuous sixteenth year, Alice reverts to her previously cheerful and upbeat attitude.
... when Bob and Charlie start training together, Bob's drive leads him to become the superior athlete.
Alice's wheelchair is the source of everyone's inspiration, not Alice herself. Anyone who sits in the wheelchair will automatically be revealed as a hero.
Bob sucked at everything before he obtained his disability. Now he's The Ace—star student, great Paralympic athlete, and Friend to All Living Things with a hot girlfriend.
Until they obtain disabilities, everyone in Troperville sucks at everything.
Zig Zagged: Alice is morally grey and performs acts that would not be considered moral while disabled, but people still treat her like an amazing influence.
Alice and Bob are both shown as normal characters, not particularly wiser or any more talented than anyone else in the cast, and story arcs that have nothing to do with their disabilities.
Enforced: "This show isn't just inspirational enough - let's put in a disabled character."
Daisy, for purposes of her own, tries to emphasize and highlight how cheerful and angelic Alice is, how tragically beautiful, probably for purposes of emotional manipulation on a third party.
Bob, an average-caliber athlete, enters in an athletics competition, hoping that, in the judges' eyes, the fact that he's performing as well as the other athletes, but on crutches!, will give him an edge.
Defied: Bob's parents raise him to think that his disability is not inspiring and he is not anymore special than anyone else, because they don't want their son to be a stereotype.
Discussed: "Everybody acts like it's a big deal every time Alice breathes, just because she's in a wheelchair."
When Alice was a little girl, she was very sick and everyone thought she would die, including her. That led to her thinking from a very early age about the afterlife, death, and the meaning of it all. She is very used to putting on a brave and smiling face for her parents, and hardly ever lets her real feelings show.
Bob is a perfectionist, driven by his desire to be great because he hates being pitied. He internalizes hurtful ideas about disabled people and becomes convinced that other disabled people must be weak if they aren't as good as he is. Eventually, this leads to a breakdown, as he has still defined his entire life according to his disability.
Furthermore, both Alice and Bob's disabilities aren't left vague and formless; Alice suffers from the long-term effects of rickets, with accompanying symptoms, and Bob has cerebral palsy from a birth defect, with accompanying symptoms.
... but then, after a tumultuous adolescence, Alice's experiences have led her to develop a wise and open-hearted view of the world. She is able to express her true feelings, including anger, fear, and sadness, even to her parents. Since her friends rely on her so much for advice, she decides to become a therapist.
... but then, Bob finds out that his teammates (and his buddy Charlie) are still there for him, whatever he needs. Secure in their friendship, he lets go of his need to be perfect and tries to gain a new perspective on life.
As with Deconstructed, Alice and Bob's disabilities aren't vague and formless. Also, they both have a complete, visible life outside of their disability, or else there'll be a very good reason why.