1. You can only change yourself
The best way to address the situation is to change how you perceive it and how you react to it.
2. Draw your boundaries
Be clear on what you will tolerate and what you will not tolerate -- then stick with it.
3. Be upfront about where you stand
People aren't mind readers, and sometimes they may not be aware that they are infringing on your space or taking up a lot of your time.
4. Be firm when needed
If the person does not stick within the boundaries, then enforce them.
5. Ignore them
If you just ignore them, they don't have a choice but to seek out someone else.
6. Don't take it personally
Most of the times, these people behave the same way around others too.
7. Observe how others handle them
The next time you are with this person, get someone else into the conversation too. Observe how the other party handles it.
8. Show kindness
Often times, they act the way they do because they are looking for an empathetic ear.
9. Help them
Beneath the facade is really a cry for help.