Hi! Quick question for someone who has worked as an internet/marketer for a satrtup... as minority partner in a company, how do you prevent yourself from simply being "fired" or dissolved?

The reason? I dont like to work on commission (as they first proposed) in internet marketing because 90% of the work is done in the first 10% time of the company's services. So either I can charge 10x the rate for my work or I think a partnership is much more realistic to the rewards of the company. But then if they do make me say, a 10% partner with commissions only on net sales above current net sales (to be fair so I only earn what I am bringing in), how do I prevent them from getting rid of me next year when the company is flourishing and they think they dont need me anymore?

Btw, I am not making any capital investment/donation, only services and time, and most of my time will be on internet marketing, and some on general marketing and business advice since I am more experienced in some things than my partner. I am favoring the partnership type of deal over commission because as we all know, internet marketing for a small site is very start heavy, and unless I charge a lot, I like the motivation factor and future payoff more than making a few bucks now. Besides he has very little sales now and very little funds, so he wouldnt be able to pay me my regular hourly/weekly rate for something like this.