What's the word or description for...

[rara67]

...something that lives off something else but that something else needs the original something to exist. The case is where I am a tenant and I am my landlord's main source of income. If they evict me, I couldn't find anywhere else for the same price so couldn't run my business but if I could leave (lottery win, or offer of free rent) then they would probably go under...sorry not much to go on. Think its usually applied to nature rather than commerce!

Do you have a symbiotic relationship? (Need to check in dictionary!)

Parasite?

Symbiosis

Parasite isn't mutually beneficial!

co-dependent?

Thanks that's just what I needed. I think that symbiotic is more nature but co-dependent sounds more appropriate to describe a business relationship. Thank again - you'll make me look really smart!! Have a good weekend

Commensal?

I think 'co-dependent' has quite negative connotations; it's often used to describe toxic relationships where one person has a substance abuse problem and their partner is an enabler. Having reread your OP, you'd be better off with 'symbiotic'. If the relationship is very beneficial for you both then I think 'synergistic' would be appropriate.

Just googled; the word you are looking for might be 'mutualism'.

Mutually financially dependent.

IMHO.

I agree that "co-dependent" has a negative connotation as it has become a term of art in the substance abuse context. I'd go with "symbiotic" or "synergistic" for a positive connotation or "mutualism" or what Prism said for a more neutral effect.

hmm, it's a sort of mutually assured destruction situation, I guess that's not quite the phrase you are after!

Symbiotic if you just co-exist without either really benefiting or being disadvantaged; mutualism is if there is benefit on both sides; parasitism is if one benefits to the other's disbenefit.