Link two Pi together

Hi all. My latest stupid idea…
I would like to get a Pi-top. But I want both network.

My first idea was to get a Vonet device. But what if I use a Pi 3 under Linux to get the connection (and Linux software with RDP) from another Pi 3 under RISC OS?

Technically, it’s possible to link two Pi together with a simple Ethernet cable, and without a hub or switch. Just need to provide the right addresses to each computer. And Linux can share its Wifi connection to a wired one.

The only problem will be to know if the USB port of a Pi is strong enough to power another Pi (without any devices connected on it). And if the Pi-top has enough power for this. 6 hour of battery life would be enough for me if I can have both Linux and RISC OS from the same computer :)

No idea is stupid enough…
In the past I have link two RISC OS Computer with a Ethernet crossover cable directly and connect one of them via ComCentre with the WWW and set “Act as an IP router” in the Network settings.
It shouldt also possible with Linux and Wifi but I have not try.

For power you can link a 5 V and a Ground pin of the GPIO headers.

I found the time for a short try. Power two Pi (2 and 3) with a cable like this with Pi-Top… Pi-Top with Pi3 is working with PiTopOS and P2 with RISC OS with a seperat Display. Not linked yet. After round about one hour “play around” the battery lost about 12%.