fixen
to shoot up
In the drug scene, the colloquial term for injecting hard drugs intravenously, especially heroin.
Er hat in seiner Jugend eine Zeit lang gefixt.
For a while in his youth, he used to shoot up.

to fix / to shoot up / to hook
Loading your saved state.
to shoot up
In the drug scene, the colloquial term for injecting hard drugs intravenously, especially heroin.
Er hat in seiner Jugend eine Zeit lang gefixt.
For a while in his youth, he used to shoot up.

The meaning of 'fixen' depends extremely strongly on context. Pay close attention to the situation and the other words in the sentence in order to understand it correctly.
Er muss das Problem schnell fixen.
He has to fix the problem quickly.
The meaning 'Drogen spritzen' (to inject drugs) belongs to the colloquial language of the drug scene. In this context, the verb is often used without an object and has very negative connotations.
In dem Film wird gezeigt, wie die Hauptfigur anfängt zu fixen.
The film shows how the main character starts shooting up.
In the meaning 'reparieren' (to repair), 'fixen' is a colloquial loanword from English ('to fix'). It is always used with an accusative object that is being repaired.
Ich muss kurz mein Fahrrad fixen, bevor wir losfahren können.
I have to quickly fix my bike before we can leave.
When 'fixen' means that someone is excited about something, the structure is 'Etwas fixt jemanden' (something hooks someone). The subject is the thing, e.g. a series or a game, that triggers the excitement.
Dieses neue Videospiel hat meine Freunde komplett gefixt.
This new video game completely hooked my friends.
to inspire / enthuse
'begeistern' and 'fixen' can both express that someone develops a strong interest in something. 'begeistern' is the normal and neutral word: a film, a hobby, or an idea can inspire someone or get someone enthusiastic. 'fixen' is very colloquial and sounds stronger. It can mean that someone is so enthusiastic that they can hardly get away from it. Because 'fixen' also has other meanings and can quickly sound slangy, 'begeistern' is a better fit in most situations.

Nach dem ersten Training war Max vom Klettern total gefixt.
After his first training session, Max was totally hooked on climbing.
Die neue Musiklehrerin begeistert die Klasse mit einfachen Liedern.
The new music teacher inspires the class with simple songs.