Type O × Type OBlood type compatibility
Two anchors. Formidable when pointed the same way, exhausting when pointed at each other.
For entertainment only. Blood type compatibility (ketsueki-gata aishō) is a popular Japanese cultural belief and is not supported by science. Please don’t use it to make real relationship decisions.
What two Type Os recognise in each other
Instant mutual recognition — someone who decides, someone who shows up, someone who says the real thing at the table. Both are used to carrying groups, and there's a rare comfort in not having to carry this one. There's also, from minute one, a low hum of competition neither would admit to.
What works
When the goal is shared, this is the most effective pair on the chart. Both push, both deliver, both are generous with credit and with actual help. Socially they're a machine: the party happens, the trip gets booked, the friend in trouble gets picked up from the station at midnight.
Where it breaks
When the goal isn't shared. Two people who each expect to set direction will find something to contest — the route, the plan, the interpretation of a conversation that happened last year. Neither backs down easily, and both would rather win the exchange than end it. The fights are loud, short, and repeat.
By situation
- Dating — Passionate and combustible. Strong while there's a common project; corrosive when the only project is each other.
- At work — Great as peers with separate territories. Bad as two leads on one thing.
- As friends — Loyal, generous, and lifelong — with a running argument about something that stopped mattering years ago.
One thing that helps
Split the map. Name whose call it is per domain, in advance. You are not disagreeing about the restaurant.
Every pairing
All ten combinations of A, B, O and AB — each page covers both points of view.
- A × O High
- A × AB High
- B × AB High
- A × B Tricky
- B × O Steady
- O × AB Steady
- A × A Steady
- B × B Steady
- O × O Steady
- AB × AB Steady
Prefer the grid? See the full 4×4 compatibility chart.