Sketch is an obsessive and somewhat delusional young woman. When officially first introduced in Sketch, she is seen to have a huge infatuation, bordering on pathological, with Maxxie Oliver who she goes to school with. It is unclear when or how her infatuation developed, but several factors which can lead to obsessive love seem to have been experienced by Sketch, such as her feelings of vulnerability which may stem from the fact that she acts as a carer for her mother who suffers from multiple sclerosis. She harbours some rage towards her mother, who she feels has never looked after her properly.
On top of this, she seems quite distant from a lot of her peers and most likely has feelings of unworthiness or low self-esteem. She sees Maxxie as someone who can make her life much better, and is so 'in love' with him that she pretends to her mother that they're boyfriend and girlfriend, as well as flattening her chest to make her appear more masculine and attractive to Maxxie (as Maxxie is gay). She also displays manipulative and deceitful behaviour showing little regard for anyone she hurts in her delusional quest to become Maxxie's girlfiend. As her story progresses, she later shows some regret for how she acted, though continues to be besotted with Maxxie, and even enters into a relationship with Maxxie's friend Anwar, in hopes to stay close to him.
Sketch's profile on E4's official Skins website.