I am using
node.Owner
To print out things like user name, for instance to print the first name out (which is a custom field) it is simply.
{{ node.Owner.field_first.value }}
However if I try to do the same for the user picture I get an error. I have tried
{{ node.Owner.user_picture.value }}
{{ node.Owner.user_picture}}
{{ node.Owner.user_picture.0.value }}
{{ node.Owner.user_picture.content }}
None of these work ?