Most of my siblings, vying for our parents' attention, took a different approach. They became performers. They sought ways to please our parents and would put on a show - singing and dancing - to find approval. Their reward was expressions of love from the adults who would brag about them to outsiders.
I'm sure each of you who had siblings had similar disparities in your own families. Now as members of the family of God, we are no longer in a dysfunctional family. We are not in competition with each other for our Heavenly Father's favors. His love for us is unconditional -- once we have been adopted into His family by the blood of the Covenant.
The middle child syndrome can be seen in the church by Christians who put God's love to the test by acting up. They continue in their sins while proclaiming that God's grace covers all their rebellious ways. Others become performers, thinking they must find work to do in ministry - must keep busy - in order for Christ to approve of them.
Neither attitude is the fruit of one who has been set free from the bondage of sin.
"For the law of the Spirit of life in Christ Jesus has made me free from the law of sin and death." - Rom 8:2
The two extremes: legalism and license, are childish notions. And we are commanded to "Put away childish things." Jesus Christ finished the work. The Holy Spirit has empowered us to overcome sin. God the Father accepts us based upon the righteousness of His Son if we are in Christ.
So relax; grow up. Enjoy your liberty. You are OK.
"Trust in the LORD, and do good;
Dwell in the land, and feed on His faithfulness.
Delight yourself also in the LORD,
And He shall give you the desires of your heart.
Commit your way to the LORD,
Trust also in Him,
And He shall bring it to pass.
He shall bring forth your righteousness as the light,
And your justice as the noonday.
Rest in the LORD, and wait patiently for Him."
-- Ps. 37:3-7a
"Thus says the LORD:
'Stand in the ways and see,
And ask for the old paths,
where the good way is,
And walk in it;
Then you will find rest for your souls.'"
-- Jer. 6:16a