I've got two Azure Virtual Machines which both reside in the US-East-2 region. For billing reasons I cannot put them into a virtual network (each VM is on a different subscription) but I can connect from VM1 to VM2 using VM1's Public IP.
Will Azure route the traffic internally or will I get billed for regular internet traffic?
I think your answer is here on the Data Transfer Pricing page:
Is data transfer between Azure services located within the same region charged? No. For example, an Azure SQL database in the same region will not have any additional data transfer costs.
Note that Azure subscriptions are containers for access control and organization. I don't think there is a fundamental difference between connecting services within a single subscription vs. between services in separate subscriptions.
