What was the relationship between Silas and Timothy?
Silas and Timothy stayed together in Beroea and later caught up with Paul. Their names appear next to Paul’s in the letters to the Thessalonians. Acts 17:14; Acts 18:5; 1 Thessalonians 1:1
What the Bible says
Acts 17:14
And then immediately the brethren sent away Paul, to go unto the sea; but Silas and Timothy remained there.
1 Thessalonians 1:1
Paul and Sylvanus and Timothy: to the church of the Thessalonians, in God the Father, and in the Lord Jesus Christ.
Douay-Rheims Bible (Challoner revision), public domain.