Question: I am an editor for a trade publication with 40 years of experience in journalism. The company wants me to take a job on the events side, writing content, helping with organization, moderating panels, archiving video. They haven’t called it a promotion but it would clearly be more intense work and involve traveling to conferences every other month. I’d like to accept the offer but I want to negotiate a salary increase after a six-month review. Can I do that upfront or do I wait the six months and in either case, what kind of percentage would be equitable?

Answer: 
* Inform you manager about the Verbatim copies of code from the Internet, and tell that you see a potential legal liability there
* Explicitly state in commit messages which of his commits you fixed
* Your manager listened to you once, so the next time a huge and messy commit comes which breaks something working and could have been caught by the test, you write an email to your coworker with the manager in CC stating that you need he should show you on his machine how he tested the code and how it works.
* When he submitted something which breaks and leaves during the office hours, you go to the manager shortly after he left and ask him to locate your coworker, stating that you would prefer if the coworker helps integrating the code - state that you can do it alone, but it may take more time and state which of your tasks is delayed by this.
* In case this continues, take notes over one week how much work integrating your coworkers mess has caused you, with specific incidents, go to your manager and state that you "can handle it without him"
As other recommend, I would ask somebody higher up if I could start CCing him in all your exchanges besides documenting everything in a source code system. 

Obviously, if you working for the two, your colleague does not need to do it. However, it seems a bit odd he taking such a relaxed stance of missing so many hours of work and days off in the middle of an intern project...it is as he knows he cannot fail.

I would investigate if he has relatives inside. I have seen my share of pet employees over the years. It is usually not that hard to find out. Maybe you were setup together for a reason.

Welcome to the fantastic world of the real world and office politics!

Assuming no foul play, at the end of the day, someone is failing you not making regular meetings to guide you both and assess the state of the project.

PS. A possible course of action if that is a University endorsed internship is probing on the University side if you can change for another place. The odds are slim, but without asking it is not possible to find out.