You can invite this player to your team, and that way help each other survive. To form a team, you must target the player you wish to invite.
Open the Team Window by clicking the Team button on the menu.
Press the 'Recruit' button to invite the player to your team. If the player accepts the invitation you will see his health and nano energy as red and blue bars in the Team Window. A team can consist of up to six people.
F1 through F6 will quickly target yourself (F1) and your teammates (F2-F6). This is useful for performing actions, and executing nano programs, that require targeting.
You can chat with your teammates in private, regardless of their location, through the team chat channel.
Clicking the Friends button on the menu will open your Friends Window, the location of your friends list and all available chat channels. Left-click the team channel to activate it. The channel in red is your current output.
There is an option to disable any chat channel you should not wish to listen to.