I had the problem that just using fprintd on my system as an authentication-method lead me to a state where I always had to input my fingerprint or fail three times until I could finally type my password. In the pam.d-config-files not fprintd should be used but fingerprint-gui. That works then also for the TTYs and when you have registered several fingers, you can use them all and not only your right index-finger for authentication. There is an Arch-How To for this: https://wiki.archlinux.org/index.php/Fingerprint-gui