I built a business from nothing to eight figures, put $850K of my own money into it, and watched a co-founder divert revenue, abandon the enterprise, and leave 35+ shareholders carrying the loss. The lawsuit that followed cost $120K and three years. It was dismissed in February 2025.
Here is the part I have made peace with. The red flags were there early. I read them as quirks instead of patterns. These are the ones I would never ignore again.
Red flag one: vagueness about money
A partner who is fluent about vision and fuzzy about numbers is telling you something. Money discipline is a values question, not a skills question. The person who treats the company account as a personal cushion at $50K will do the same at $5M, only the number that disappears is larger. Financial vagueness early is the single loudest signal, and the one I most wish I had taken literally.
Red flag two: how they behave when things go wrong
You learn who a partner is the first time the business is under pressure, not when it is winning. Do they take ownership or assign blame. Do they protect the company or themselves. The problem is that this usually reveals itself after you have already signed everything. Which is exactly why you stress-test for it before you do.
The cost of a bad partner is not the equity you give away. It is everything that gets built on top of the wrong foundation.
Red flag three: resistance to structure
A trustworthy partner welcomes a written agreement, vesting, and clear financial separation, because those protect everyone, including them. A partner who treats structure as a lack of trust is the partner who most needs it imposed. Resistance to protection is not loyalty. It is a preview of the leverage they intend to keep.
What I built instead
After the dismissal, I rebuilt everything around protection: a vetting system, financial separation by default, and the assumption that good structure is a respect mechanism, not an insult. The $850K is gone. What it bought is a way of choosing and protecting partnerships that I now hand to every founder I work with, so the price I paid becomes a price they never have to.