MITM / Proxy for Character devices

I have a character devices file , say /dev/X and I would like to capture every interaction which goes in and out of /dev/X. I'm looking for a way to create some kind of MITM/Proxy to that file. **Edit:** Regarding what X is, it is FM interface over android. So /dev/fm is the character device file. The end goal is to intercept any command that is sent to this file.