At its basis, this relationship consists of two parties abiding by a mutual agreement and providing something the other needs or wants. But ego, greed, irresponsibility, external family dynamics, and so many other things can turn this seemingly simple relationship into a complex one. Because the stakes are high for both individuals should things fall apart, the potential for conflict between these characters is high.

Each relationship is different, depending on the people involved, their history together, their individual personalities, and a host of factors. Below are a wide range of dynamics that can accompany this relationship. Use the ideas that suit your story and work best for your characters to bring about and/or resolve the necessary conflict.

Mutual respect in the form of both parties abiding by the rules of the legal contract and holding up their end of the bargain
An empathetic landlord who understands that life happens, choosing to extend grace to a tenant in need
A landlord making their tenant a priority by taking care of facilities issues promptly
A tenant being a responsible steward of the landlord's property and leaving it in the same or better condition than when they moved in
A landlord checking in periodically to see how the tenant is doing (rather than only reaching out when there's an issue)
A landlord and tenant resolving to work through their problems rather than bringing in an outside source, such as a lawyer or the police
Both parties addressing concerns respectfully
A tenant consistently being late or not paying their rent
An absentee landlord who shows no concern for the tenant's living conditions
A landlord having no sympathy for an emergency situation that temporarily puts the tenant behind
A vengeful tenant who resolves to make the landlord pay for a real or perceived slight
A landlord being quick to evict their tenants
A landlord or tenant avoiding the other party's phone calls and correspondence
Dishonesty; the tenant lying about when they'll have this month's payment or the landlord saying they called a repair service when they didn't
A nitpicky landlord who won't let the tenant make any changes to personalize the property
A tenant who does what they want (painting walls crazy colors or changing the landscaping) and pleads ignorance, deciding to ask for forgiveness instead of permission

An extended family member needing a place to stay, and the tenant having to hide their presence from the landlord
The tenant being unable to make rent due to extenuating circumstances (being laid off, an accident that generates hefty hospital bills, etc.)
The landlord dying and the property being passed along to an apathetic, greedy, overbearing, or inept heir
A tenant's personal life causing friction (a drunken ex showing up frequently, a reckless son or daughter causing property damage, etc.)
A landlord trying to cut corners (by hiring a cheap locksmith who creates a security vulnerability, for example) and causing problems for the tenant
A biased landlord seeking to get rid of a tenant for unfair reasons
The tenant getting a pet and needing to keep it a secret from the landlord
Rent being raised
The landlord tightening restrictions or establishing new rules that make the living situation less desirable
A disaster (a sinkhole, fire, a pest infestation, etc.) requiring extensive remodeling that requires the tenants to live elsewhere for a while
The tenant's family struggling with health issues they believe are coming from the facility—from mold, asbestos, lead paint, etc.